Top seed John Isner advanced to the semi-finals of the US Men’s Clay Court Championship in Houston after beating South Korea’s Chung Hyeon 7-6 (5), 6-4 on Friday.
In his last four match, the big-serving American will take on his compatriot and defending champion Jack Sock, who is seeded fourth this time around.
Sock sealed his place in the last four with a 6-4, 6-4 victory over former Australian Open runner-up Marcos Baghdatis of Cyprus.
Earlier in the day at the River Oaks club, Argentina’s Juan Monaco beat fifth-seeded Sam Querrey 6-4, 6-4.
Monaco will take on third-seeded Spaniard Feliciano Lopez, who beat another American Tim Smyczek 6-2, 6-3.