Serra came back after losing the first set to down Spain's Albert Montanes 4-6, 6-1, 7-6 (7-3) in one of Sunday's two main draw matches.
In the other, Gulbis prevailed when Argentina's Juan Ignacio Chela retired in the second set with a right wrist injury as Gulbis was leading 7-5, 2-2.
The top seeds for the Paris Masters -- the final ATP Masters event of the year -- are Roger Federer and Novak Djokovic. Federer defeated Djokovic Sunday for the title at the Swiss Indoors and both have byes into the second round.
Djokovic prevailed at last year's Paris event, beating Frenchman Gael Monfils at Palais Omnisports.