(CNN) -- Germany's Tommy Haas upset Roger Federer in straight sets to win the ATP tournament on the grass courts of Halle Sunday.
Federer was bidding for his sixth title at the Wimbledon warm-up tournament but had no answer to his 34-year-old opponent, who won 7-6 (7-5) 6-4 in front of his home fans.
It was Haas' second Halle title after winning in 2009 and his 13th on the ATP Tour.
He has made a remarkable recovery after hip surgery which sidelined him for 14 months and he started 2012 outside the top 200 in the world.
His victory will see him rise to 51st in the rankings and he is set to be a dangerous outsider at Wimbledon.
"This has been one of the best weeks of my career, but I reckon I won't really appreciate what's happened until this evening," he told the official tournament website.
"If someone had said to me beforehand that I was going to beat Roger Federer, probably the best player of all time, I would have thought they were mad!"
Federer, coming off a semifinal loss to Novak Djokovic at the French Open, took a 3-1 in the opening set but proceeded to lose three successive games as Haas broke back.
The German took a close tiebreaker and a single break to lead 5-4 in the second set left him serving for the title.
When Federer hit a return long it was Haas who raised his arms in triumph after 95 minutes of gripping action.
Federer, who will now head to the third grand slam of the season bidding for a seventh Wimbledon crown, was magnanimous in defeat.
"Tommy was the better player and he deserves this win," said the 30-year-old Swiss maestro.