Defending UEFA Champions League winners Liverpool faced an opening defeat to their 2019-20 continental campaign against Napoli as the new season kicked-off in full throttle. Meanwhile, 2018-19 semifinalists Barcelona were held to a 0-0 draw on Matchday 1. Serie A side Inter Milan were held to a 1-1 draw by Slavia Prague. Ligue 1 outfit Lyon also drew to Zenit Saint Petersburg. Frank Lampard faced an early defeat in his European debut as manager, as Chelsea lost to Valencia. Red Bull coasted past Genk, meanwhile, Ajax defeated Lille in style. Also, RB Leipzig defeated Benfica.
Inter 1-1 Slavia Prague
An injury-time equaliser from Nicolo Barella denied Slavia Prague a famous Champions League win over Inter at San Siro on Tuesday.
The champions of the Czech Republic were not expected to escape from a daunting Group F that also contains Borussia Dortmund and Barcelona but looked on course for a deserved victory in Milan through Peter Olayinka.
Slavia could have added to their tally and were punished in second-half stoppage time, as Barella's shot bounced through a crowded box and into the left-hand corner to ensure the game finished 1-1.
Inter started slowly until Stefan de Vrij headed over when unmarked six yards out, before Lautaro Martinez fired narrowly wide.
Danilo D'Ambrosio's header was denied by Ondrej Kolar, who was then lucky not to give away a goal as he made a mess of an attempted clearance but Inter were largely lifeless in the first half.
Kolar had to react smartly to stop Stefano Sensi's cross creeping in and then keep out Martinez's rebound, before Kwadwo Asamoah avoided a red card following a VAR review for a foul on Ibrahim Benjamin Traore, who had to be substituted.
It was his replacement, Jaroslav Zeleny, whose first-time shot was superbly saved by Samir Handanovic only for Olayinka to pounce and turn the ball high into the net to give Slavia their shock lead.
Buoyed by the breakthrough, Slavia continued pressing high and should have scored a second through Lukas Masopust, who blazed over the bar from the edge of the box.
It was substitute Barella who rescued a result for Antonio Conte's side, his half-volley finding a way into the net after Sensi's free-kick had crashed off the crossbar.
Lyon 1-1 Zenit
Memphis Depay's penalty saw Lyon come from behind to draw 1-1 at home to Zenit in the opening round of Champions League fixtures.
Zenit scored the first goal of the group stage through Sardar Azmoun but Lyon hit back six minutes into the second half with a penalty earned and scored by Depay.
Both teams pushed for victory in Tuesday's Group G game but were unable to find a late breakthrough.
Lyon started on top with Moussa Dembele curling a shot narrowly over the crossbar, although Branislav Ivanovic had wasted a free header at the other end.
Marcelo then nodded wide from a Depay corner as Lyon continued to press, but Zenit opened the scoring against the run of play in the 41st minute.
A clever one-two with Artem Dzyuba on the edge of Lyon's box sent Azmoun through and he poked his finish past onrushing goalkeeper Anthony Lopes.
Lyon pulled level early in the second half, though, Depay coolly converting a penalty he won himself by drawing a foul from Magomed Ozdoev – who had only just come off the bench - in the area.
The equaliser boosted Lyon and Jeff Reine-Adelaide should have put them in front after Zenit were carved open, the former Arsenal youngster instead firing wide from the edge of the box.
That opportunity proved the clearest chance to score a winner for either side, with the spoils shared after Depay failed to make the most of being played in by Reine-Adelaide.
Chelsea 0-1 Valencia
Ross Barkley missed a late penalty as Chelsea's Champions League campaign under Frank Lampard began with a 1-0 loss to Valencia in Group H.
Valencia's off-the-field issues have overshadowed their on-field exploits since Marcelino's sacking last week, but Albert Celades' side bounced back from their 5-2 defeat to Barcelona with a resilient performance at Stamford Bridge.
With Jasper Cillessen in fine form and Mason Mount's injury having compounded Chelsea's frustrations, the Blues' frailties were exposed once more when Rodrigo Moreno prodded in Dani Parejo's free-kick with16 minutes remaining.
VAR came to Chelsea's rescue when the referee decided to award the hosts a spot-kick for a Daniel Wass handball, but substitute Barkley - who overruled Willian to take the penalty - struck the bar.
Fresh from his hat-trick against Wolves, Tammy Abraham should have done better in the sixth minute when he latched onto Cesar Azpilicueta's cross - Cillessen making the save.
Chelsea were dealt a blow soon after, Mount's Champions League debut cut short as he failed to overcome an ankle injury inflicted by Francis Coquelin's robust challenge.
Willian's volley drew a brilliant stop out of Cillessen on the stroke of half-time and Valencia's goalkeeper had more work to do when he kept out Marcos Alonso's free-kick.
But just after Lampard had gambled in throwing on Olivier Giroud for Kurt Zouma, Valencia struck.
Having stole a march on his markers, Rodrigo just managed to make enough contact on Parejo's superb pass.
Chelsea's fortunes looked to have turned with four minutes remaining when referee Cuneyt Cakir handed them a lifeline having looked at the touch-line screen, but Barkley failed to keep his composure.
Salzburg 6-2 Genk
Teenager Erling Haaland announced himself on the European stage with a stunning first-half Champions League hat-trick as Salzburg thrashed Genk 6-2.
The 19-year-old, son of ex-Manchester City and Leeds United defender Alf-Inge Haaland, became only the eighth player to score three times on debut in Europe's elite competition.
Hwang Hee-chan, Dominik Szoboszlai and Andreas Ulmer were also on target for the Austrian champions as they moved top of Group E.
Norway international Haaland, who had already scored 14 times domestically heading into the match, took just two minutes to open his Champions League account when he fired low into the left corner from inside the box.
He soon doubled their advantage when a quickfire counter-attack ended with the teenager being sent clean through and he made no mistake, tucking confidently inside the right post.
A poor Genk clearance was then punished as Hwang steered a shot low inside the right post after being fed by Zlatko Junuzovic.
Genk gave themselves a glimmer of hope five minutes before the interval courtesy of a sliding finish from Colombia defender Jhon Lucumi after Salzburg had failed to deal with a set-piece.
However, two quickfire Salzburg goals - the first a close-range finish from Haaland to complete his hat-trick before Dominik Szoboszlai converted Takumi Minamino's cross - ensured the contest was over before the break.
Haaland became the first teenager to score more than once on his Champions League debut since Wayne Rooney's hat-trick for Manchester United against Fenerbahce in September 2004.
Mbwana Samatta's header pulled one back for the visitors, yet Ulmer restored the four-goal advantage midway through the second half with a tidy finish after good work again from Junuzovic.
Samatta was initially shown a red card for a challenge on Junuzovic only for the decision to be overtuned by VAR.
Napoli 2-0 Liverpool
Dries Mertens and Fernando Llorente struck late to earn Napoli a 2-0 win at home to holders Liverpool in the first game of the Reds' Champions League defence.
Carlo Ancelotti's men won the corresponding fixture last term with Mertens' spot-kick and Llorente's injury-time goal enough to ensure history was repeated in the Group E clash at the Stadio San Paolo on Tuesday.
Andy Robertson was deemed to have tripped Jose Callejon in the box and, after VAR ratified the penalty decision, Mertens squeezed his penalty past Adrian in the 82nd minute.
Liverpool rode their luck in reaching the knockout rounds in 2018-19 and Jurgen Klopp's men will again have to bounce back from an away loss to Napoli this year after Llorente's first goal for the club sealed all three points.
Napoli had an early strike ruled out for offside when Hirving Lozano headed home the rebound after Adrian's excellent double save from Fabian Ruiz.
Sadio Mane's shot was saved by Alex Meret in the 20th minute - Liverpool recording their first shot on target in the game having failed to manage any in last season's visit.
And the Reds should have gone into the break 1-0 up, Firmino heading wide a fine James Milner cross on the Brazil forward's 200th Liverpool appearance.
Napoli had the first big chance of the second half, Adrian showing superb reactions to prevent Mertens from turning in Fabian's deep cross, then Mane overhit a pass to Mohamed Salah as Liverpool broke at speed.
Liverpool were starting to build pressure and, after successive errors from Kalidou Koulibaly and Kostas Manolas handed him a sight of goal in the 65th minute, Salah's drive was turned around the post by Meret.
Napoli's goalkeeper had to deny Mane again as Liverpool looked to finish strongly, but when Callejon jinked into the box he went over Robertson's outstretched leg to win a penalty.
Mertens had to wait for the VAR check, but calmly drilled his strike past Adrian, with Virgil van Dijk's terrible error in stoppage time ensuring former Tottenham striker Llorente could ease home a second.
Ajax 3-0 Lille
Last season's beaten semi-finalists Ajax opened their 2019-20 Champions League campaign with a convincing 3-0 win over Lille on Tuesday.
Erik ten Hag's side – who were denied a place in the final by Tottenham last term – were in dominant mood against their Ligue 1 opponents and looked well placed to claim all three points from the outset in Amsterdam.
Quincy Promes headed them into an 18th-minute lead before Edson Alvarez scored his first goal for the club five minutes after the interval.
Nicolas Tagliafico added a third with a thumping header after 62 minutes as the Dutch champions stormed into pole position in Group H.
Ajax started on the front foot and went agonisingly close to taking the lead in the 14th minute, Hakim Ziyech's thunderous half-volley crashing back off Mike Maignan's right-hand post.
They did not have to wait long to go ahead, though, as an unmarked Promes met Tagliafico's deep cross with a powerful header just four minutes later.
Lille responded well to that early setback and should have pulled level moments before the interval. Jonathan Bamba picked out Jonathan Ikone after a surging run down the left but Andre Onana got down well to keep out his low effort, with Victor Osimhen hooking the rebound over the crossbar.
The hosts looked sharp at the start of the second period, Ziyech testing Maignan low down to his left with a fierce drive.
Their positive approach was rewarded in the 50th minute when David Neres slid Alvarez in down the right after a flowing team move and the Mexican superbly lifted a shot across the Lille goalkeeper from a tight angle to double their advantage.
Tagliafico ensured there would be no dramatic comeback from Lille when he made it 3-0 shortly after the hour mark, superbly heading home Ziyech's outswinging corner.
Yusuf Yazici crashed an effort against the post late on as Lille tried in vain to restore some respectability to a scoreline that did not flatter the hosts.
Benfica 1-2 RB Leipzig
Timo Werner struck twice to give RB Leipzig a deserved 2-1 victory over Benfica in their Champions League Group G opener on Tuesday.
Germany international Werner took his tally to seven goals in six games in all competitions this season with two clinical finishes inside nine second-half minutes at the Estadio da Luz.
Werner opened the scoring with a low arrowed shot and then tapped home from close range with 12 minutes remaining.
Benfica provided some late drama when Haris Seferovic scored in the 84th minute, but Leipzig held on for a win that puts them top of the pile after Zenit and Lyon drew.
Benfica coach Bruno Lage, who was serving a touchline ban after being sent off during last season's Europa League semi-final second leg against Eintracht Frankfurt, put his faith in younger players as Tomas Tavares made his full debut and Ferro and Jota started.
Leipzig looked the more accomplished side and thought their early intensity had produced an opening goal when Werner crossed for Emil Forsberg to slot home, only for VAR to disallow it for offside.
Both sides had chances in added time at the end of the first half; Benfica's Raul de Tomas headed straight at Leipzig goalkeeper Peter Gulacsi, while at the other end Yussuf Poulsen curled wide.
Benfica keeper Odisseas Vlachodimos made a vital interception from a teasing Poulsen cross after the interval to deny the lurking Werner.
It served as warning and with 69 minutes on the clock Werner took his chance, firing a low, angled shot into the net after Poulsen's lay off.
Werner added a second when Marcel Sabitzer crossed and the Germany striker steered in a goal that was ruled out for offside until VAR overturned the decision.
Benfica got one back when Seferovic slid in to guide the ball home at the back post, but it was too little, too late as Leipzig claimed maximum points.
Borussia Dortmund 0-0 Barcelona
Lionel Messi's second-half return from injury was not enough to inspire Barcelona to Champions League victory at Borussia Dortmund as Marc-Andre ter Stegen played a vital role in securing a 0-0 draw on Tuesday.
Talismanic forward Messi made his first appearance of the season after recovering from a calf injury, though he was a peripheral figure for Barca, who only secured a point thanks to Ter Stegen saving Marco Reus' penalty.
Dortmund edged a first half that was cagier than many might have expected from a contest between two typically free-flowing sides, though proceedings were more stretched after the break.
Reus spurned a glorious chance to give the hosts the lead in the 57th minute when seeing his spot-kick kept out by Ter Stegen and then Julian Brandt hit the crossbar from long distance as Barca held on to a point.
Dortmund began the brighter of the two sides, but Barca crafted the first opening as Gerard Pique's glancing header in the 13th minute flashed right across the face of goal.
They had to rely on Ter Stegen to remain level 12 minutes later, however, the German thwarting Reus from close range after he latched on to Thorgan Hazard's incisive disguised pass.
Dortmund went close again six minutes before half-time, but Jadon Sancho fired just over from 20 yards after being teed up by Paco Alcacer at the end of well-worked counter.
Ter Stegen was Barca's saviour once more just before the hour mark, producing a brilliant save down to his left to keep Reus' penalty out after Nelson Semedo had trodden on Sancho's foot.
Messi was introduced soon after for the quiet Ansu Fati, who became Barca's youngest player in the Champions League.
Dortmund still looked livelier, as Alcacer and Reus shot over from close range, before Brandt's 30-yard drive hit the bar, but Barca escaped unscathed.
