Pakistan, Aug. 7 -- Alexander Zverev and Daniil Medvedev both suffered upsets against Dutch opponents in the second round of the Canadian Open on Wednesday, while fellow title contender Taylor Fritz also crashed out in Montreal.

World number three Zverev, playing his first match since losing to Jannik Sinner in last month's Wimbledon final, was beaten 6-7(3) 6-2 6-4 by Tallon Griekspoor, who arrived in Canada with one win in his last eight tour-level matches.

The defeat comes as a setback to the German's preparations for the US Open, which begins on August 30.

"I've been very close to throwing in the towel a couple of times," world number 69 Griekspoor said after claiming his third victory over French Open champion Zverev.

"I've been ...