Top seed David Ferrer rallied from a slow start to edge out Mikhail Kukushkin at the Hamburg Open.
World No 53 Kukushkin had never beaten Ferrer but he gave himself a great opportunity in the second-round encounter as he raced into a one-set lead.
However Ferrer slowly regained control and won his last five games on the bounce to seal a 2-6 6-3 6-2 victory.
Fellow seeds Tommy Robredo and Santiago Giraldo came through their second-round encounters unscathed, however Marcel Granollers crashed out.
Decider
Third seed Robredo, the 2006 champion, overcame Daniel Gimeno-Traver, 6-2 7-5, while Giraldo, the No 11 seed, beat Benoit Paire 7-6 (8-6) 6-2 in 83 minutes.
Eighth seed Granollers, though, failed to take a match-point chance in the decider as he lost out 2-6 6-3 7-5 to Dominic Thiem.
In first-round action, Leonardo Mayer was a 6-3 6-2 winner over wild card Peter Gojowczyk, Juan Monaco routed Pere Riba 6-3 6-1 and Jerzy Janowicz beat Albert Ramos-Vinolas 6-0 7-5.
Martin Klizan dug deep to outlast Igor Sijsling 6-4 3-6 6-0, Alexander Zverev thumped Robin Haase 6-0 6-2, while Lukas Rosol was 6-4 2-1 up when opponent Julian Reister retired hurt.