Karen Khachanov defeated teenager Jakub Mensik 7-6 (14-12), 6-4 in straight sets at the Qatar Open for his sixth ATP Tour victory.
Khachanov (27, Russia), ranked 17th in the world, did not drop a set in this tournament.
Mencik, an 18-year-old Czech player, became the first teenager to reach the Qatar Open final.
Mensik hit 16 aces in the final, and Khachanov said, “For a moment, I thought I was playing against John Isner and not Jakub Mensik today.”
Mensik, ranked 116th in the world, had defeated Andy Murray and world No. 5 Andrei Rublev en route to the final.
Elsewhere, Jasmine Paolini came from behind to defeat Anna Kalinskaya at the WTA Dubai Open.
Despite trailing 5-3 in the deciding set, the Italian won 4-6, 7-5, 7-5 for her first WTA 1,000 victory.
Kalinskaya (Russia), ranked 40th in the world, was serving for the match in the third set but fell short of match point.
Paolini scored 16 of the remaining 19 points and won the remaining four games to seal the victory.
“I’m really surprised,” Paolini said. “I’m really happy. It was a really tough match. She’s playing unbelievably.
“It was really tough coming back. I tried to stay positive at every point. I’m really proud of myself.”
The 28-year-old, ranked 26th in the world, won her first WTA singles title at the 2021 WTA250 Portoroz.
She has reached three finals since then in her quest for a second WTA title, but lost all of them until Saturday’s victory over Kalinskaya.
In the Russian preliminary round, she defeated world No. 1 Iga Swiatek in the semifinals, ending Iga Swiatek’s winning streak with seven wins, and entered the final in great shape.
However, Kalinskaya, who eliminated Paolini at the Australian Open in January, was unable to repeat that form in the final.