Second seed Granollers was on court for just 75 minutes in a comfortable 6-1 6-4 triumph over wildcard Yann Marti in round two of the ATP 250 clay-court event in Gstaad.
The world number 28 - who is ranked 184 places above the Swiss - was particularly impressive in a first set in which he won 80 per cent of points on his first serve.
A back-and-forth second set saw five breaks of serve, but Granollers was able to showcase his superiority to advance to a quarter-final tie with fellow Spaniard Pablo Andujar.
Andujar secured his place in the next round with a routine 6-3 6-3 success over Blaz Rola.
However, there was no such luck for another Spaniard in the form of Garcia-Lopez, as the third seed was defeated by Juan Monaco for the second year running at the tournament.
Garcia-Lopez may be ranked 73 places above the Argentinian, but Monaco extended his head-to-head record over the 31-year-old to six wins and just two losses in a 6-2 2-6 6-4 success.
Monaco's compatriot Federico Delbonis will not join him in the quarter-finals, however, as Brazil's Thomaz Bellucci toppled the fifth seed in a 6-4 6-4 victory.
Bellucci batted away three break-point chances from Delbonis and took two of his own for a win in a time of one hour and 24 minutes.
Elsewhere, Swiss wildcard Henri Laaksonen delighted the home fans by defeating France's Gianni Mina 7-6 (7-5) 7-6 (7-3) in their first-round clash.
The match had started on Tuesday but was halted for bad light, with Laaksonen now facing a clash with the seventh-seeded Robin Haase in round two.