Top-seeded Stan Wawrinka laboured to a 4-6 6-3 7-6 (7-4) win over Dustin Brown to reach the quarter-finals of the Moselle Open on Thursday.
Starting his campaign at the indoor hard court tournament, the French Open champion was able to convert just one of his 11 break chances against Brown, who beat Rafael Nadal in the second round at Wimbledon this year.
Second-seeded Gilles Simon, a two-time former champion in the north eastern city, enjoyed a more comfortable start as he dispatched fellow Frenchman Edouard Roger-Vasselin 6-4 6-2.
Sixth-seeded Martin Klizan also advanced to the quarter-finals with a 6-4 7-6 (9-7) win over Canadian Vasek Pospisil on Thursday.
The 35th-ranked Slovakian, playing in Metz for the first time, needed nearly two hours to win a match that featured just one break of serve.
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Klizan will next face fourth-seeded Guillermo Garcia-Lopez of Spain, who rallied past French wild-card entry Pierre-Hugues Herbert 4-6 6-2 6-4. Herbert hit 13 aces but dropped his serve three times.
"It was a tough match against Vasek, because he is a great player," Klizan said after defeating the Wimbledon quarter-finalist. "He has one of the best serves in the world. I tried to focus on the return and in the tiebreak I was a bit lucky."
Also advancing were Nicolas Mahut and Germany's Philipp Kohlschreiber, Wawrinka's next opponent.
Mahut fired 24 aces to move past seventh-seeded Adrian Mannarino 6-4 6-7 (7-5) 6-3 and set up a meeting with third-seeded Jo-Wilfried Tsonga.
