Juan Martin del Potro outlasted Daniel Brands of Germany 6-7 (5), 7-6 (4), 7-6 (6) at the Erste Bank Open on Wednesday in the top-seeded Argentine's first match since recovering from a right wrist injury that sidelined him for a month.
The three-hour match was marked by strong serving - Del Potro hit 30 aces, Brands 32 - and both players held serve throughout.
''I played a nice match after a month without competition,'' said the eighth-ranked Del Potro, who played just one Davis Cup match because of the injury after losing in the U.S. Open quarterfinals to Novak Djokovic in early September.
''I served really well every moment of the match,'' said Del Potro, who failed to convert any of his 10 break points. ''I will train, practice all day, I need to improve day by day.''
Brands, a semifinalist here last year, closed out the opening set with an ace but double-faulted when Del Potro had set point in the second.
Del Potro, who is still in the race to qualify for the season-ending ATP World Tour Finals in London, won the decider on his second match point when Brands sent a backhand just wide.
Del Potro will play either Austrian wild-card entry Dominic Thiem or Marinko Matosevic of Australia in the quarterfinals. Thiem, ranked 394th, beat Lukas Lacko of Slovakia 7-6 (3), 6-3 in the first round.
Gilles Muller of Luxembourg defeated two-time champion Jurgen Melzer of Austria 6-3, 3-6, 7-6 (4) to reach the quarterfinals.
Muller broke the fourth-seeded Melzer twice in the opening set but had no break points on the Austrian's serve afterward. He converted his first match point with a return winner in the third-set tiebreaker.
''It's bitter to lose 7-6 in the third,'' Melzer said.
The 2009 and 2010 winner, who had a first-round bye, had not lost his opening match in his home event since 2004.
''He returned extremely well and that took me by surprise,'' Melzer said. ''I was just not good enough today in the decisive moments.''
In first-round play, Ernests Gulbis of Latvia hit nine aces while beating Somdev Devvarman of India 7-6 (6), 6-3. Gulbis next plays second-seeded Janko Tipsarevic of Serbia.
Also, Donald Young of the United States won his fifth match of the season, defeating Fabio Fognini 7-6 (8), 6-3.
Young was two breaks up before the fifth-seeded Italian won four straight games to take the opening set into a tiebreaker. Young, who dropped from 38th to 187th in the rankings this year, saved six break points in the second.