Juan Martin del Potro made short work of Mischa Zverev at the Mexican Open on Tuesday, sweeping the German aside 6-1, 6-2 as he cruised into the last 16 in just over an hour.
The sixth seed broke Zverev six times to set up a match with four-time winner in Acapulco David Ferrer of Spain.
Australian Open semi-finalist Hyeon Chung of South Korea, meanwhile, saw off Donald Young 7-6 (7-5), 6-1.
Fourth seed Jack Sock continued his poor run of form, losing to 21-year old compatriot Ernesto Escobedo in two sets 7-5, 7-6 (7-3). It marked Sock’s second loss to a young American in consecutive weeks after his defeat to Reilly Opelka at the Delray Open.
Escobedo’s reward is a last 16 match up with Chung.
Another seed to make an early exit was reigning champion Sam Querrey. He lost out in three sets in a close fought match to Australia’s Matthew Ebden 6-3, 1-6, 7-6(7-5).
Kei Nishikori was also sent packing as he lost to in-form Canadian teen Denis Shapovalov 7-6(7-3), 3-6, 1-6.
.@denis_shapo outlasts Kei Nishikori!
— Tennis TV (@TennisTV) February 28, 2018
The Japan former world number four had plenty of chances, but failed to capitalise as his 18-year old opponent saved nine of ten break points on his serve.
“I just kept fighting. I got my break, and the momentum went from there,” said Shapovalov, who made only his second ever ATP World Tour semi-final last week in Florida. “It’s tough to play him. He’s so solid. He moves extremely well. It was an extremely difficult match for me.”
Last week’s winner from Rio, Diego Schwartzman made a strong start, seeing off Fernando Verdasco 6-2, 6-4 in a repeat of Sunday’s Rio final. The Argentine will meet America’s Ryan Harrison in the last 16.
World number two Rafael Nadal, who was scheduled to play Feliciano Lopez, pulled out with a hip injury.
It is the same injury that forced Nadal to retire from his Australian Open quarter-final against Marin Cilic in January.