Top-seeded Pablo Andujar was among Thursday's second-round winners at the $485,000 Serbia Open.
The recent Casablanca champion Andujar had to come from behind to beat Italian Filippo Volandri 4-6, 7-5, 6-2 at Tennis Center Novak. The Spanish Andujar piled up six service breaks en route to victory.
Andujar's quarterfinal opponent on Friday will be Czech Lukas Rosol, who outplayed Romanian veteran Victor Hanescu 7-6 (7-4), 6-3 on Day 4.
Another second-round result saw France's Benoit Paire overcome Spaniard Guillermo Garcia-Lopez 4-6, 7-5, 7-5.
Third-seeded Finn Jarkko Nieminen was leading Croatian qualifier Antonio Veic 5-3 in the first set when rain forced a suspension of their match. The eventual winner will meet Paire on Friday.
Some other quarterfinals will pit second-seeded Italian Andreas Seppi against eighth-seeded Gilles Muller of Luxembourg and fourth-seeded former Wimbledon runner-up David Nalbandian of Argentina against Brazilian Joao Souza.
Belgrade serves as a tune-up for the French Open and will pay its newest champ $88,000.