HOUSTON, April 14 (UPI) -- John Isner
recorded 11 aces and survived two tiebreaks Friday to reach the semifinals of the U.S. Men's Clay Court Championship.
Isner defeated Ryan Sweeting 7-6 (7-1), 7-6 (7-4) to set up a semifinal meeting with Feliciano Lopez.
Lopez had a 6-4, 2-2 lead when Carlos Berlocq retired with a injury.
The other semifinal will send Michael Russell against Juan Monaco.
Russell, who defeated No. 1 seed Mardy Fish in the third round, advanced with a 6-1, 5-7, 6-3 victory over Ryan Harrison.
Monaco fought off Kevin Anderson 7-6 (7-4), 7-5.
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