Los Cabos Open top seed Tomas Berdych produced a stirring display to come from a set down to beat Adrian Mannarino and secure his place in the last four.
Wimbledon semi-finalist Berdych trailed 4-1 in the final set but erased that deficit to prevail 4-6 6-3 6-4 in Mexico on Thursday.
Mannarino appeared on track to reach the final four but Czech star Berdych reeled off five successive games after two hours and seven minutes on court.
"It was a good test for me because he was really playing well and I had to fight for every point. You appreciate these matches more than winning easily," said Berdych.
"I just had to stay patient and keep believing in myself."
Awaiting Berdych in the semis is Thanasi Kokkinakis, after the Australian wildcard beat Taylor Fritz 7-6 (7-5) 6-2.
Another Wimbledon semi-finalist, Sam Querrey, is also through after he secured victory over Vincent Millot.
Second seed Querrey was far too good as he accounted for the Frenchman 6-1 6-3, while his next opponent Damir Dzumhur came from a set down to oust fourth seed Feliciano Lopez 6-7 (2-7) 6-4 7-6 (7-2).