The result meant Austrian Juergen Melzer, who could only have booked a place in the London showdown if he won the title and Roddick failed to progress beyond the third round, is out of the race. Only Spain's Fernando Verdasco still has an outside chance of denying eight-seed Roddick his place in London.
Roddick got off to a flying start, opening a 2-0 lead and comfortably holding serve to bag the first set. Gulbis proved more consistent in the second set but bowed out when he netted a routine forehand to lose the tiebreak 10-8 after saving three match points.
Roger Federer produced his 'A Game' on Wednesday and Andy Murray had to switch to 'Plan B' on the super-fast indoor court to reach the third round. Federer stepped up his bid to win the Paris tournament for the first time by sending down a barrage of winners in a 6-4, 6-4 hammering of Frenchman Richard Gasquet.
"I'm battling with a little bit of fatigue, but I believe the confidence can get me through a long way here," the top seed said after notching up his 10th consecutive win. While Federer was booking a date with Czech Radek Stepanek in double quick time, Murray struggled to find his groove against Argentine David Nalbandian in the Bercy arena.
Unable to dent Nalbandian's game, the Briton switched tactics and his decision to serve and volley paid off as he came from a set down to sink the former champion 2-6, 6-4, 6-3.
"I haven't played on a quicker court since I've been on the tour," Murray told reporters. "I was struggling to control the ball, and then changed the tension on my rackets ... and felt a lot more comfortable."
Nalbandian visibly tired after having his serve broken at the end of the second set. At 2-2 in the third the Briton called for the trainer to massage his right wrist and that galvanised him to take four of the last five games.
"I think I should be okay for the rest of the tournament," the Scot said. "I managed to finish the match and normally, if your wrist injury is bad you can't." Murray next plays 13th-seeded Croatian Marin Cilic. Swedish fifth seed Robin Soderling made light work of Simon, beating him 6-4, 6-0 in just over an hour to set up a third-round match against Stanislas Wawrinka.