Rafael Nadal, the seven-time champion seeded second, dropped his opening service game against the unpredictable Paire, ranked a career-best 33rd with the Spaniard finding himself trailing 2-0 on the clay of the Real Club de Tenis.
But as the morning match wore on, Nadal found his familiar clay court groove, lifting the first set in a tie-breaker and dominating in the second to take his third-round win.
“It wasn’t a brilliant match but winning was the most important thing,” said Nadal. “It’s a long day today, so straight sets is not a bad way to start. “My next opponent will be playing at a high level and I need to improve over how I played in the morning.”
The World No 5 will now play unseeded Albert Ramos after his compatriot put out Japanese sixth seed Kei Nishikori 6-4, 7-6 (7/4). Nadal, sidelined for seven months until February with a knee injury, appeared to be well on the road to recovery after his loss in the Monte Carlo final last week to Novak Djokovic.
The 26-year-old Nadal improved to a 37-1 career record in Barcelona with his only loss against current Davis Cup coach Alex Corretja in the 2003 second round.
He now stands 23-2 this season and 18-2 on clay. Meanwhile, 2004 winner Tommy Robredo of Spain knocked out third seed Tomas Berdych 3-6, 7-6 (7-5), 6-3.