Paire, who was sidelined for three months, won 6-4, 5-7, 6-4 and will meet another Spaniard in Guillermo Garcia-Lopez, after the eighth seed beat Carlos Berlocq 6-2, 7-5.
Fourth seed Marcel Granollers is also safely through after defeating fellow Spaniard Albert Ramos 6-3, 7-6 (3), but fifth-seeded Joao Sousa of Portugal lost 6-7 (7), 7-6 (5), 6-2 to qualifier Roberto Carballes Baena, who is playing in only his second ATP World Tour event.
Carballes Baena faces Andrey Kuznetsov next. The Russian led 6-2, 3-1 against Jiri Vesely when the 20-year-old retired due to illness.
Pablo Carreno Busta beat Aleksandr Nedovyesov 3-6, 6-1, 7-6 (3).