The 26-year-old silver-medallist from the Rio Games, however, remained in the hunt for the bronze and will be competing against China's He Bing Jiao
Reigning world champion P V Sindhu's hopes of securing India's first ever Olympic gold in badminton came crashing down as she slumped to a straight-game defeat against world no.1 Tai Tzu Ying of Chinese Taipei in the women's singles semifinals in Tokyo on Saturday.
The 26-year-old silver-medallist from the Rio Games, however, remained in the hunt for a bronze and will be competing against China's He Bing Jiao in the third place play-off at Musashino Forest Plaza on Sunday.
One of the most consistent players, who has claimed medals in all big-ticket events in the last five years, Sindhu couldn't counter Tai Tzu's deception with her aggressive game, going down 18-21 12-21 here.
This is Sindhu's 14th loss to the Taiwanese second seed in 19 meetings, having also lost to her in the last three face-offs.
Tai Tzu tried to play an aggressive game, cramping Sindhu with her sharp returns from near the net.
The two played some exquisite rallies with Sindhu equalling her opponent and also unleashing a few smashes to lead the opening game for most parts.
She was up 7-3 with Tai Tzu committing a few unforced errors and entered the interval with a healthy 11-8 lead.
Tai Tzu, however, quickly erased the deficit after the break. She started putting doubts in her opponent's mind with her deceptive strokeplay.
Sindhu kept retrieving everything thrown at her and gathered points whenever she had the chance to attack.
The duo moved neck and neck from 11-11 to 18-18 before Tai Tzu unleashed a drop and then pushed one away from Sindhu's reach to lead for the first time.
Soon Tai Tzu grabbed two game points and sealed it with a straight down the line forehand smash.
Brimming with confidence, Tai Tzu used her angled returns to telling effect in the second game. Sindhu tried to play her attacking strokes but her cross court smashes, attacking tosses and angled returns -- all ended up going wide and long as the Taiwanese made it 11-7 at the break.
The world no.1 dished out some delightful strokes, including a cross court smash on Sindhu's backhand, an overhead straight smash, a loopy precise toss at the backline, to march ahead as Sindhu ran out of ideas.
She eventually sealed her place in the Olympic final with a flick serve and a cross court return to Sindhu's backhand.
On Friday, Sindhu, seeded sixth, had beaten Japanese world no.5 Akane Yamaguchi in the quarterfinals.
Earlier, men's singles player B Sai Praneeth and the men's doubles pair of Chirag Shetty and Satwiksairaj Rankireddy had failed to qualify for the knockout stage.