NICE, France - Dominic Thiem hit 11 aces Friday to upset second-seeded John Isner and set up a final against Leonardo Mayer at the Open de Nice.

The big-serving Isner also had 11 aces and saved seven of eight break points in the first set but lost the first three games of the second set to slump to a 7-6 (5), 6-3 loss at the clay-court tournament.

The 42nd-ranked Thiem, who is chasing his maiden ATP tour title, said "you don't play a final every week, so I am really happy. But if I lose tomorrow, I won't win the tournament. I will do everything I can to win my first title."

The fourth-seeded Mayer defeated Borna Coric 6-4, 6-3 in the other semifinal after fending off 11 break points.