Atlanta - Three-time defending champion John Isner won the tallest match-up in ATP World Tour history, beating Reilly Opelka 6-7 (5), 6-4, 6-2 on Saturday in the Atlanta Open semi-finals.
The 6-foot-10 Isner had 22 aces against the 6-foot-11 Opelka, the 18-year-old Michigan player who recently replaced the former University of Georgia star as the tour's tallest player.
The top-seeded Isner has won 15 straight matches in the hardcourt event and reached the final for the sixth time in seven years. He has 10 tour titles, the last late year in Atlanta.
Opelka was playing his third tour event. He lost in the first round in the first two.
Isner will face second-seeded Nick Kyrgios of Australia, a 6-3, 3-6, 6-3 winner over Japan's Yoshihito Nishioka in the afternoon semifinal.