The top-seeded Spanish superstar breezed to a 6-3, 6-2 victory over Argentine qualifier Federico Delbonis on the clay courts of Vina del Mar, swatting four aces en route to the win.
Nadal made his long-anticipated return to tennis after sitting out seven months with a knee injury. The current world No. 5 chose to make his reappearance in South America, where he hasn't competed since 2005 as an 18-year-old.
Also Wednesday, defending Vina del Mar champion and No. 3 seed Juan Monaco of Argentina succumbed to Frenchman Guillaume Rufin in an upset, 7-6 (7-3), 6-4.
The wrap-up of first-round play saw No. 5 seed Albert Ramos, sixth-seeded Paolo Lorenzi and Gimeno-Traver record victories.