Leonardo Mayer is officially a titleholder… And, he did it by taking down the top seed.

The 27-year-old Argentine tenista upset David Ferrer 6-7 (3), 6-1, 7-6 (4) in the Hamburg Open final on Sunday to claim his first ATP title.

The 46th-ranked Mayer saved five of the eight break points he faced and converted five of his seven chances to beat Ferrer, who is ranked No. 7 in the world, in the clay-court tournament.

“I can’t believe it,” said Mayer. “I was able to do it against Ferrer, who is one of the best players on this surface. I’m really happy and it still hasn’t sunk in that I won.”

Mayer had not dropped a set in five matches to reach the final, while Ferrer was bidding for his 22nd title.

“He was better in the match,” said Ferrer. “I think I was little bit nervous in the important moments and he played more aggressive than me, and nothing else.”