Top seed Tomas Berdych claimed a quarter-final berth with a comfortable win at the Los Cabos Open as Fernando Verdasco crashed out.
Berdych moved into the last eight courtesy of a 6-3 6-1 victory against Australian youngster Akira Santillan.
The Czech star wrapped up proceedings in under an hour, winning 20 of 24 points on his first serve at the ATP 250 event on Wednesday.
American second seed Sam Querrey overcame countryman Evan King 6-4 4-6 7-6 (7-2), fourth-seeded Spaniard Feliciano Lopez eased past Matthew Ebden 6-4 6-4 and seventh seed Adrian Mannarino accounted for Bjorn Fratangelo 6-1 6-1.
However, fellow seeds Verdasco and Albert Ramos-Vinolas were not so fortunate.
After surviving a scare and two match points on Tuesday, sixth seed Verdasco lost 1-6 6-2 6-4 to Vincent Millot.
Spanish third seed Ramos-Vinolas, meanwhile, was beaten 7-6 (7-5) 6-4 by Taylor Fritz.
Thanasi Kokkinakis trumped Peter Polansky 4-6 6-3 7-6 (7-4) and Damir Dzumhur was leading 5-3 in the first set when Quentin Halys retired hurt.