German second seed Philipp Kohlschreiber survived a second set scare to see off Frenchman Benoit Paire and book his place in the quarter-finals of the Moselle Open in Metz.
The world number 18 appeared to be coasting to victory after taking the first set 6-2 but he was broken twice in the second before recovering to post a 6-2 1-6 6-1 victory.
Fifth seed Andreas Seppi of Italy had a much more serene passage to the last eight as he needed just 62 minutes to see off French qualifier Vincent Millot 6-2 6-1.
Seventh seed and home favourite Gael Monfils battled past fellow Frenchman Nicolas Mahut 7-6 (7/4) 7-5, while Russian veteran Nikolay Davydenko was a 7-5 6-4 winner over Luxembourg's Gilles Muller.
Third seed Marcel Granollers of Spain was the biggest casualty of the day, retiring when trailing 7-6 (7/3) 2-2 to Croatia's Ivo Karlovic, while American Jesse Levene ended the run of German lucky loser Michael Berrer 6-4 3-6 6-0.