Roddick will next face either Jo-Wilfried Tsonga or Novak Djokovic
Andy Roddick reached the Paris Masters last eight and secured one of the three remaining places for the Masters Cup with a 6-3 7-5 win over Gilles Simon.
The American will finish this week ranked no lower than seventh with the world's top eight qualifying for the season-ending tournament in Shanghai.
France's Jo-Wilfried Tsonga boosted his chances of qualifying for Shanghai with a 6-4 1-6 6-3 win over Novak Djokovic.
Favourites Andy Murray, Roger Federer and Rafael Nadal all progressed.
Second seed Federer had little problem in defeating Croatia's Marin Cilic 6-3 6-4, Murray looked comfortable despite not being on top form during a 6-3 7-6 victory over Spain's Fernando Verdasco, while Spaniard Nadal beat local favourite Gael Monfils 6-3 6-2.
Murray, bidding to become the first player to win three straight Masters events, will play defending champion David Nalbandian after the Argentine easily beat compatriot Juan Martin Del Potro 6-4 6-0.
Federer will next play James Blake, who needs to reach the final to qualify for Shanghai, after the American beat Germany's Philipp Kohlschreiber 6-4 6-4.
Tsonga will face Roddick in the last eight and the Frenchman will have to beat his opponent if he is to qualify for Shanghai.
"If I manage to stay in shape physically, I will go from strength to strength in this tournament," said Tsonga.
"I really want to do something big here - I always said I feel right at home at Bercy (stadium)."
Roddick needed five match points to get the better of Simon, eventually winning the match when the Frenchman went for a forehand winner and the ball clipped the net and bounced out.
The American said he had to dictate the play against Simon.
"It wasn't going to do me any good to play patty-cake back and forth with him," said Roddick.
"I'm not as quick as he is and I'm not as consistent as he is. It actually made for a pretty simple game plan."
A break in each set was enough for Wimbledon champion Nadal to see off Monfils although he had to stave off five break points in the third game of the second set.
Nadal, who now has won all three of his matches against Monfils, will face either Czech Tomas Berdych or world number six Nikolay Davydenko.