The Spaniard was a 6-3 7-6 (7/3) winner in the showpiece game of the day, ensuring there were no shocks in the Malaysian capital.
Sixth seed Denis Istomin looked in impressive form as he sauntered into round two by easing past Pablo Andujar 6-3 6-2.
Alex Bogomolov Jr booked a clash with top seed David Ferrer after dispatching British qualifier Dominic Inglot in straight sets.
The Russian converted just a quarter of his 12 break point opportunities but it was enough to see off his opponent, who is predominantly a doubles player, 7-5 6-3 in 77 minutes.
Former world number three Nikolay Davydenko advanced via the same score against lucky loser Sanam Singh and Alejandro Falla was 7-6 (7/4), 4-2 ahead against Rajeev Ram when the American retired with a hamstring injury.
Vasek Pospisil was the first player to reach the quarter final stage after seeing off Michael Yani 6-3 7-5 in a little under two hours, with Julien Benneteau later following him by disposing of Matthew Ebden.