After losing all of Tuesday's play to the weather, things looked to be going the same way on Wednesday until conditions improved at the ATP 250 clay-court event - allowing eight of the nine matches to go ahead.
Only Philipp Kohlschreiber's clash with Jan-Lennard Struff was put back even further, with the pair to come back on Thursday morning.
Garcia-Lopez started well against opponent Marco Cecchinato to take the opening set and although the Italian battled back, the seed recovered to record a 6-4 1-6 7-5 win.
The Spaniard took advantage of the qualifier's poor second serve to win 53 per cent of points in the match, while also converting 67 per cent of his first serve points.
Santiago Giraldo was the only other seed in action on Wednesday and he cruised past Croatian qualifier Mate Delic in straight sets.
Giraldo - seeded seventh - only faced two break points on his own serve during the match while converting four of the six he created himself.
The Colombian will now face another qualifier in round two after Philipp Davydenko beat Blaz Rola 6-4 7-6 (10-8).
Daniel Gimeno-Traver, Louk Sorensen and Yann Marti also booked second-round places with straight-set wins, while others were made to work harder to secure their progression.
Home favourite Benjamin Becker had to come from a set down beat Frenchman Benoit Paire 3-6 6-2 6-2 to set up a match with face Federico Delbonis in round two.
Wednesday's only other match saw Lukas Rosol battle with world number 285 Alexander Zverev for one hour 43 minutes and through two tie-breaks before securing victory.
The Czech wasted five set points in the first, and two match points in the second before progressing 7-6 (9-7) 7-6 (11-9).