Stop us if you've heard this one before: Atlanta United has dug themselves a major hole in the CONCACAF Champions League tournament.

On Wednesday night, before a loud and perhaps daunting crowd at Estadio BBVA Bancomer in Mexico, United fell to top-seeded Monterrey in Leg 1 of the quarterfinal round, 3-0.

In retrospect, fell might have been generous with the above description. 

Put another way, United collapsed in the final 15 minutes, allowing a seemingly mundane 1-0 defeat to become a three-goal-deficit monster.

As such, at the bare minimum, United must pull off a 3-0 win over Monterrey for next week's rematch in Atlanta ... otherwise, they'll be eliminated from the Champions League bracket.

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So, what are the differences between United's Mexico loss and the 3-1 defeat to CS Herediano two weeks ago in Costa Rica?

a) By not scoring a road goal versus Monterrey, United won't have access to a simple tiebreaker for next week (based on road goals). 

For the Herediano rematch, Atlanta needed only a 2-0 victory to advance to the Champions League quarters.

b) The chances of Monterrey rolling over in Atlanta next week, to the tune of a 4-0 defeat (similar to the Herediano rout) are extremely long.

Bottom line: United may be the defending MLS Cup champs, but they've been anemic on the road to date, mustering just one goal over three away matches (one MLS, two CONCACAF).

Monterrey's fleet of quick and aggressive defenders were seemingly too much for United, which tallied only five shots (three from Gonzalo Martinez; zero from Josef Martinez) and notched one shot on target.