Victor Riu shot 1-under-par 70 on Sunday and won the Swiss Challenge by three strokes.
Riu finished 72 holes at Golf Sempachersee at 19-under 265 for his maiden Challenge Tour win.
"I'm so happy, but it hasn't quite sunk in yet," said the 28-year-old. "I struggled a lot at the start so I'm delighted that I was able to produce a strong finish."
American Brinson Paolini shot 65 and tied for second in his first tournament as a professional. He finished alongside Adam Gee, who shot 67, at 16-under par.
Pedro Oriol (64), Sihwan Kim (66) and Jamie McLeary (70) shared fourth place at minus-15.
Riu began the final round with a 4-stroke lead, but he was 2-over par through 10 holes, allowing Gee to pull even.
At the 15th, Riu rallied with a birdie, and Gee, playing in the group ahead, bogeyed, giving the former a 2-stroke cushion.
Riu then locked up the win with back-to-back birdies at 16 and 17, rendering Gee's eagle-bogey finish obsolete.
"My putting was a lot better on the back nine, and it was important to get that birdie on the 17th to play the last with no pressure," said Riu. "It's a tricky hole with a difficult green, and it's easy to make bogey. On the 17th there was still only one shot in it, as I didn't know Adam had bogeyed the last, so it was a relief to make a birdie there."