Georgian world number 16 Nikoloz Basilashvili became the first player to defend the Hamburg Open title since Roger Federer in 2005 with a three-set win over Russian Andrey Rublev.
Basilashvili, 27, hit 26 forehand winners in a 7-5 4-6 6-3 victory.
Rublev's serve came under pressure in the first and third sets, Basilashvili converting four of 15 break points.
Despite victory, Basilashvili has lost ranking points as he won last year's event after going through qualifying.
Basilashvili went on to secure the title at the ATP Tour 500 clay-court event after saving two match points in his semi-final against Hamburg-born world number five Alexander Zverev.