The Denver outfit twice came from behind to eventually defeat El Salvador's Isidro Metapan 3-2 at Dick's Sporting Goods Park on Wednesday night.
Isidro's Allan Kardeck, who was later sent off, opened the scoring by converting from the penalty spot in just the second minute before the Rapids leveled in the 16th minute thanks to a Macoumba Kandji header.
The determined Salvadorans again hit the front, surprisingly to most, when Paolo Suarez pounced on a defensive error from goalkeeper Matt Pickens and right-back Kosuke Kimura before chipping home neatly 25 minutes into the contest.
But from then on, it was all Colorado, who used their one man advantage to level at 2-2 through Kandji who grabbed his second on the stroke of half-time.
Five minutes after the re-start, the Rapids were a goal clear after Andre Akpan's left-footed shot rustled the back of the net, which was enough to give Gary Smith's a positive start in Group B.
The win by Colorado added to LA Galaxy's 2-0 victory over Motagua, Seattle Sounders 4-1 drubbing of Comunicaciones and FC Dallas' narrow 1-0 away win at Pumas UNAM, which made them the first US team to win in Mexico.