Top seed Andy Roddick served a barrage of aces to beat fellow American Robby Ginepri 7-6, 7-6 and reach the Lyon Grand Prix quarter-finals on Thursday.
"Robby certainly played better than me today and my serve obviously made the difference," said the former world number one, whose 26 aces included one when Ginepri had a set point in the second tiebreak.
American Roddick faces Robin Soderling for a place in the last four. The seventh-seeded Swede easily swept past Belgian qualifier Christophe Rochus 6-1, 6-2 in only 46 minutes.
Soderling beat Roddick in the quarter-finals in Memphis this year in their only encounter so far.
"It is going to be hard for me," Roddick said.
The American, who is sixth in the race for the season-ending Masters Cup, is bidding for one of the three remaining places in the eight-man Shanghai event in November.
French fourth seed Gilles Simon, runner-up in the Madrid Masters last Sunday, struggled to beat Italian Andreas Seppi 7-6, 5-7, 6-4. He faces French wildcard Josselin Ouanna, 182nd in the ATP rankings, in the quarter-finals.
Simon, ninth in the race, could boost his chances of going to China if he reaches the last four in Lyon.
Another Frenchman, third seed Jo-Wilfried Tsonga, reached the quarter-finals with a 6-2, 5-7, 6-3 win over veteran compatriot Fabrice Santoro.
He takes on Spaniard Juan Carlos Ferrero in the last eight after the former French Open champion took less than an hour to beat eighth seed Paul-Henri Mathieu 6-4 6-1.
By contrast, Richard Gasquet, who played in the Masters Cup last year, suffered another frustrating defeat when he was beaten 6-4, 3-6, 7-6 by Belgian Steve Darcis.
The second-seeded Frenchman served for the match in the third set but failed once again in a season to forget.
"If I end my season in the top 20 it will be a huge miracle. I can't wait for the end of the season. I want to be a new player in 2009," said Gasquet, who is ranked 15th.
Darcis plays another Frenchman, Julien Benneteau, in the quarter-finals.