METZ, France (AP) Top-seeded Dominic Thiem of Austria beat German qualifier Peter Gojowczyk 7-5, 7-6 (2) to reach the Moselle Open quarterfinals on Wednesday, furthering his bid to reach the season-ending ATP World Tour Finals for the first time.
Thiem retired in the fourth round of the U.S. Open against Juan Martin del Potro two weeks ago because of a problem with his right knee.
Moving freely this time, the 10th-ranked Thiem hit 12 aces and did not face a single break point on his serve.
Three of the eight slots for the Finals - held in London in November - are still up for grabs, and the 23-year-old Thiem was in seventh place before this tournament.
Next up for Thiem is sixth-seeded Gilles Muller of Luxembourg, who had nine aces in a 6-4, 6-2 win against Georgian Nikoloz Basilashvili.
Frenchman Julien Benneteau also reached the last eight with a 6-3, 6-4 win against Germany's Dustin Brown, who had 14 aces but dropped his serve three times.
In remaining first-round matches, there were wins for No. 8 Nicolas Mahut of France, Malek Jaziri of Tunisia, Pierre-Hugues Herbert of France, Illya Marchenko of Ukraine and Germany's Jan-Lennard Struff.