Jurgen Melzer of Austria upset fifth-seeded Italian Andreas Seppi 6-2, 6-3 on Wednesday to advance to the quarterfinals of Zagreb Indoors tournament.
Melzer was a late entry and had to play in qualifiers, but has lost just nine games in his first two matches. Melzer - a 2010 semifinalist - served nine aces against Seppi and converted four of his seven break points.
"I am very happy with the way I played so far," he said. "I needed some matches after an early exit in Melbourne, where I lost in the first round. ... And after many injury problems I had last year now I finally play pain free."
Seventh-seeded Robin Haase from the Netherlands also advanced after rallying to beat Matthias Bachinger from Germany 7-6 (4), 3-6, 6-3.
In the remaining first-round matches, Slovenian wild card Grega Zemlja beat Croat Antonio Veic 7-6 (5), 7-6 (6), Dudi Sela of Israel defeated Andreas Beck of Germany 3-6, 6-3, 6-2, and Guillermo Garcia-Lopez of Spain ousted Daviel Evans of Britain 6-4, 1-6, 6-1.