Second-seeded Tommy Haas also advanced by beating Carlos Berlocq of Argentina 6-2, 6-4.
The German led 5-2 in the second set but dropped serve. He then wasted two match points on Berlocq's serve before using his fourth to close out the second-round encounter, hitting a cross-court forehand winner. Berlocq won his maiden title in Bastad, Sweden, last week.
Juan Monaco, the fifth-seeded Argentine who beat Haas for the Hamburg title last year, defeated Benoit Paire of France 6-3, 2-6, 6-2.
Haas next plays Fabio Fognini of Italy, who beat Marcel Granollers of Spain 6-2, 6-4. Fognini won his first title last week in Stuttgart and beat Haas in the quarterfinals.
Monaco plays third-seeded Nicolas Almagro, who beat Guillermo Garcia-Lopez 6-2, 6-3.
Fourth-seeded Wimbledon semifinalist Jerzy Janowicz of Poland was forced to retire with a right arm injury, allowing Fernando Verdasco to advance. The Spaniard, who was leading 7-5, 4-0, will next play Argentine qualifier Federico Delbonis, who beat Dmitry Tursunov of Russia 6-4, 6-3.