Wild card Tommy Haas of Germany defeated five-time winner Roger Federer 7-6 (5), 6-4 to win the Gerry Weber Open for the second time on Sunday.
The 87th-ranked Haas, the oldest player in the singles draw at 34, recovered from losing his serve in the first game by winning the first set on a tiebreaker and then getting the decisive break in the ninth game of the second set.
The second-seeded Federer was bidding for his fifth tour title of the season and his 75th coverall.
Haas got the break to earn a 5-4 lead after a lengthy rally featuring lobs, chips and a dropshot, following two unforced errors in succession from Federer allowed him to force deuce.
Haas last won the grass-court tournament in 2009.
The 87th-ranked Haas, the oldest player in the singles draw at 34, recovered from losing his serve in the first game by winning the first set on a tiebreaker and then getting the decisive break in the ninth game of the second set.
The second-seeded Federer was bidding for his fifth tour title of the season and his 75th coverall.
Haas got the break to earn a 5-4 lead after a lengthy rally featuring lobs, chips and a dropshot, following two unforced errors in succession from Federer allowed him to force deuce.
Haas last won the grass-court tournament in 2009.