John Isner and Jack Sock have set up an all American semi final at the U.S. Men’s Clay Court Championship in Houston.
Isner booked his spot in the last four courtesy of a straight sets victory over South Korean Hyeon Chung.
The top seed and 2013 champion lashed down 14 aces, won 58 per cent of his second serve points and saved all seven break points he faced to win through 7-6, 6-4.
Defending champion Sock progressed after seeing off the challenge of No. 7 seed Marcos Baghdatis.
The 23-year old extended his Houston streak to 14 straight sets won, defeating Baghdatis in their first meeting 6-4, 6-4.
The other semi final pits former champion Juan Monaco against third seed Feliciano Lopez.