Philipp Kohlschreiber captured his third ATP Tour title by winning an all-German final at the Gerry Weber Open.
He was leading 7-6 2-0 when world number 71 Philipp Petzschner retired with back pain.
A finalist in 2008, world number 49 Kohlschreiber is the fifth German champion at Halle, where Roger Federer withdrew to rest his sore groin.
Kohlschreiber has not got past the third round at Wimbledon, but will hope to do better after this win on grass.
His success at Halle puts him in the same company as compatriots Michael Stich (1994), Nicolas Kiefer (1999), David Prinosil (2000) and Tommy Haas (2009).
In the first all-German final in Germany since Hans Pohmann defeated Karl Meiler in June 1973 in Berlin, the first set was highly competitive.
But after Kohlschreiber edged the tie-break, Petzschner received medical treatment on his back.
When the second set resumed, he moved around the court gingerly before calling the match off after just an hour's play when Kohlschreiber broke for a 2-0 lead.