Germany's Philipp Kohlschreiber won the final of Halle's ATP tournament on Sunday 7-6 (7/5), 2-0 after compatriot Philipp Petzschner was forced to retire hurt with a back injury.
Petschner suffered the injury while hitting a shot with the scores poised at 5-5 in the first set.
He grimaced noticeably and although he laboured on, it was clear early in the second set that he could not continue.
On Saturday, Petzschner set up the first all-German final on the ATP World Tour since 2004 when he defeated second-seed Tomas Berdych in three sets, while Kohlschreiber booked his place in the final by beating France's Gael Monfils.
There were great expectations for the final between the two Davis Cup teammates, but in the end Kohlschreiber had relatively little to do in order to pick up the winner's check of 750,000 euros.
"It is a damned pity that Philipp could not play on. It is a shame for the fans but you could see he was really suffering," said winner Kohlschreiber.
This was Kohlschreiber's third ATP title and the first time he has won at Halle. He had previously reached the 2008 final when he was beaten by Roger Federer.