World number 50 Giovanni Mpetshi Perricard overpowered Ben Shelton 6-4, 7-6 (7/4) in Basel on Sunday to claim his first ATP 500 title.
The 21-year-old Frenchman took less than an hour and a half to add the title to the ATP 250 tournament he won in Lyon in the spring.
He is lowest-ranked champion in Basel since it became a tour-level event in 1975.
“It’s amazing to win a tournament like this. A 500 for the first time for me,” said Mpetshi Perricard who will rise to a career-high 31 when the new rankings are published on Monday.
“I just can be happy with myself, with what I did today and the past five days. It’s amazing to win here. It was a tough month for me but it’s always good when the victories are there.”
On the eve of the Paris Masters, where the two finalists are both scheduled to play, the 2.03-metre (6ft 8ins) tall Mpetshi Perricard built his victory on an exceptional service game, hitting 22 aces on Sunday, and 109 across the five matches he played in Basel.
Mpetshi Perricard, who defeated two-time defending champion Felix Auger-Aliassime and fourth seed Holger Rune on his run to the final, broke Shelton in his second service game before holding on to take the first set in under 40 minutes.
The second set was tighter, with each player holding serve before Shelton cracked at 4/4 in the tiebreak.
Mpetshi easily took the next two points, which he won, to claim the second trophy of his career.
Both players now head to Paris, where Mpetshi Perricard will face American Frances Tiafoe, ranked 15th in the world, in the first round.
Shelton will face world No.1 Jannik Sinner if he gets through his first round against a qualifier.