Qualifier Pavol Cervenak of Slovakia upset eighth-seeded Tommy Haas of Germany 6-4, 6-4 to reach the Mercedes Cup quarterfinals.
Third-seeded Bernard Tomic of Australia was also eliminated in the second round, losing to Thomaz Bellucci of Brazil. Bellucci trailed 4-1 but rallied to win 7-6 (6), 6-3.
Cervenak broke Haas in the opening game and saved seven break points in the first set.
Second-seeded Juan Monaco of Argentina breezed past Tobias Kamke of Germany 6-2, 6-3.
Cedrik-Marcel Stebe of Germany saved a match point to outlast Jeremy Chardy of France 4-6, 7-6 (8), 6-3.
AP