Dominic Thiem moved into the semi-finals of the Abierto Mexicano Telcel with a straight-sets victory over Grigor Dimitrov.
Austrian fourth seed Thiem ousted Dimitrov 7-5 6-2 after more than one-and-a-half hours in Acapulco on Thursday.
Thiem converted four of 10 break points against the seventh seed on the hard-courts at the ATP 500 event.
The final four will see Thiem meet American Sam Querrey.
Querrey battled from a set down to complete a 2-6 6-4 6-4 victory over countryman Taylor Fritz.
The Delray Beach Open winner hit 14 aces on his way to victory.
Australian Bernard Tomic advanced to the semi-finals courtesy of a straight-sets triumph against Illya Marchenko.
Tomic - the fifth seed - converted five of six break points and saved three of his own to secure a 7-5 7-5 win over his Ukrainian opponent.
Tomic will face Marchenko's countryman Alexandr Dolgopolov for a spot in the final.
Dolgopolov was rarely troubled by Robin Haase, firing down nine aces on his way to a 6-3 6-3 victory.