STUTTGART, Germany, June 14 (Reuters) - Roger Federer slumped to a 2-6 7-6(8) 6-4 loss to German veteran Tommy Haas at the Stuttgart Open on Wednesday in a disappointing comeback after the 18-times grand slam champion missed the entire claycourt season.
Federer, who opted out of the claycourt swing in order to prepare for an assault on an eighth Wimbledon crown, made a sensational start to the year by winning the Australian Open and subsequent titles at Indian Wells and Miami.
Yet despite a superb first set on grass, he lost his focus as the 39-year-old Haas, in his farewell season, proved the more consistent from the baseline and set up a quarter-final clash against countryman Mischa Zverev.
Federer, 35, grabbed an early break as his attacking topspin backhand, which had served him so well earlier this year, was again on display.
Haas, a former world number two but currently at 302, was broken again as the Swiss served out the set on his first opportunity after 22 minutes.
Federer saved four set points and wasted a match point as the German forced a third set where he broke his opponent early on.
He held on to his advantage and sealed a memorable win with his second match point. (Reporting by Karolos Grohmann; Editing by Toby Davis)