Andrey Rublev suffered a first-round defeat to Alex de Minaur on a bad day for the big names at the Rotterdam Open.
Second seed Rublev won this event two years ago but there will be no such run this time around after his 6-4 6-4 loss on Wednesday.
De Minaur broke the world number five early in each set and sealed the win at the first time of asking, moving to a 3-0 head-to-head record against Rublev on hard courts.
The Australian will face Maxime Cressy in the next round, who bounced back from his Open Sud de France final defeat by beating Tim van Rijthoven.
Jannik Sinner saw off Cressy in that Montpellier showdown and the Italian carried that form into this tournament, though he needed three sets to overcome Benjamin Bonzi.
Frenchman Bonzi forced a decider but Sinner regained his composure in the final set to prevail 6-2 3-6 6-1 and set up a heavyweight clash with top seed Stefanos Tsitsipas.
There was no such progress for Alexander Zverev, who joined Rublev in suffering an early exit.
The German came unstuck 4-6 6-3 6-4 to home favourite Tallon Griekspoor, whose four wins over top-20 opponents have all come in Rotterdam.
Stan Wawrinka, the champion in 2015 and runner-up four years later, will face the winner of that tie, after he beat Richard Gasquet 6-3 6-3 to reach the quarter-finals.
Holger Rune reached the semi-finals in Montpellier, and like Sinner the fourth seed progressed into round two, claiming a routine straight-sets victory over qualifier Constant Lestienne.
"It was tricky. It's a lot about finding the rhythm here in the beginning of the tournament and first match you have to really be on your toes, especially I played a qualifier today who already has two matches in his bag," Rune said.
"It made it more difficult, but I'm happy how I handled every situation today."
Hubert Hurkacz was another seed to fall out, with the world number 10 going down 7-6 (7-4) 7-6 (7-5) to Grigor Dimitrov.