Top seed Jessica Pegula bowed out of the Libema Open following a three-set defeat by Aleksandra Krunic in s'Hertogenbosch. (More Tennis News)
The world number five was ousted 7-6 (7-3) 6-7 (3-7) 6-4 by the 2018 winner of this event, who claimed the fifth top-10 victory of her career and advanced to the quarter-finals.
Now ranked 400th in the world, Krunic recovered from an earlier break in the opening set to force a tie-break, in which she won five straight points to draw first blood.
The Serbian also cancelled out a break before heading into another tie-break, but Pegula reeled off five points on the spin this time to level.
The American was appearing in her first tournament since April, having missed the European clay-court season with a rib injury.
However, she saw two break-point opportunities go begging in the opening game of the deciding set, and Krunic crucially broke in game three before holding out for an impressive victory.
Later on, Alex de Minaur booked his place in the quarter-finals of the competition after a straight-sets victory over Zizou Bergs.
The world number nine had to work for his victory over the Belgian, overcoming his opponent 7-5 6-4 to earn his first triumph on a grass court this year.
Bergs matched his opponent in the opening exchanges, but the Australian would eventually prevail, winning a break-point and following up without dropping a point in the final game.
De Minaur would again endure a difficult set to confirm the victory as Bergs threatened to level the encounter, but the number one seed again showed his class, finishing the contest in style.
De Minaur will face either Roberto Bautista Agut or Milos Raonic in the next round.
Data Debrief: Krunic rekindles special memories as de Minaur earns maiden grass win
Krunic will forever have an affinity with s-Hertogenbosch, where she won her only career WTA title six years ago.
And the 31-year-old claimed an impressive scalp here to reach her first WTA quarter-final since 2022 - and first on grass since that 2018 triumph.
De Minaur impressed once again, winning 86 per cent of his first serve points against the Belgian.
Their meeting in s-Hertogenbosch was the first between the pair, with De Minaur able to overcome his quarter-final defeat to Alexander Zverev at the French Open.
