Poertschach, Austria:Defending champion Nikolay Davydenko and second-seeded Andy Roddick advanced to the quarterfinals of the Hypo Group International on Wednesday.
Davydenko beat Nicolas Lapentti of Ecuador, 6-4, 6-2, while Roddick defeated Kristian Pless of Denmark 6-4, 6-3.
The top-seeded Davydenko had never before won a set against the 65th-ranked Lapentti.
"I have always played bad against him - I don't like his high topspin balls which are hard to attack," Davydenko said.
"Today, I managed to stay more patient and wait for my chances. He got tired in the long ralleys."
Davydenko, who saved all five break points against him, broke Lapentti's serve three times.
Davydenko's next opponent will be Juan Monaco of Argentina, who downed Michael Russell of the United States, 6-3, 6-1.
Roddick was in control of his match against Pless throughout, hitting six aces and dropping just nine points on his serve.
"I am serving well, but I am not happy with my performance in return games," Roddick said. "I will have to improve that part of my game to be really successful at a clay surface."
Roddick got two break points at 5-4 in the first set, and converted the second as Pless missed a forehand.
The 81st-ranked Pless needed medical treatment on a neck muscle injury early in the second set, and lost his serve again immediately afterward.
Roddick will face Gael Monfils of France in the quarterfinals. Monfils, who entered the tournament on a wild card, used a strong serve to defeat seventh-seeded Lee Hyung-taik, 7-6 (5), 6-4 in the second round.
Monfils beat Roddick at their last meeting on clay at the 2006 Masters Series in Rome.