JJ Wolf rallied for a three-set victory over No. 2 seed Frances Tiafoe, and John Isner won his 500th career tiebreaker in another straight-sets win in the quarterfinals of the Dallas Open. (More Tennis News)
Wolf reached his second career semifinal by erasing two break points in the deciding game of the all-American match, closing out the 4-6 6-3 6-4 win with his 11th ace on his second match point on Friday.
The fifth-seeded Inser is back in the semifinals in the second year of his hometown event after a 7-6(8) 7-5 win over unseeded Emilio Gomez of Ecuador.
Top-seeded Taylor Fritz faced fellow American Marcos Giron, the No. 7 seed, in another quarterfinal.
Wolf was broken twice by Tiafoe, a US Open semifinalist last year, while facing nine break points in the first set. The 24-year-old didn't face another break point until the final game.
"I usually don't think about the outcome, so I was just feeding off the energy of the fans and playing every point as hard as I could," Wolf said.
Isner is the first ATP Tour player to 500 wins in tiebreakers. Roger Federer is second with 466.
Isner and Gomez, who was in his first tour-level quarterfinal, won every point on their own serve in the tiebreaker until Isner took a 9-8 lead on Gomez's serve before serving out the first set.
Inser closed out the match with the only break, and the big-serving American hasn't had his serve broken in any of the three matches.
