Argentine Juan Monaco defeated home hope Tommy Haas 7-5 6-4 to claim his third title of the season in the ATP clay-court event in Hamburg on Sunday.
The 28-year-old Monaco, ranked 14th in the world and seeded third in this tournament, added to his titles from Vina del Mar in Chile and Houston, Texas on clay this year to bring his career tally to six.
Former world No.2 Haas, 34, was playing his second final of the season, after beating Wimbledon champion Roger Federer on grass to lift the Halle title last month.
It was his fourth consecutive defeat at the hands of the left-handed Monaco.