Bruce Arena's LA Galaxy are not the only team to see fortunes fade in CONCACAF Champions League. (Photo: Otto Greule Jr./Getty Images)

It took the first two weeks-worth of CONCACAF Champions League group matches to give Major League Soccer teams a sense of confidence and reason to believe that this edition of the tournament would the most successful MLS has ever enjoyed.

It then took just another two weeks to remind every MLS team just how tough the Champions League can be.

After starting the group stages with a dominant 8-1-1 record, the five MLS teams in the competition all looked capable of challenging for places in the knockout rounds. The next two rounds were vicious, as the Fab Five floundered to a 2-7-1 record over the second two weeks of group play.

Now, instead of thoughts of sending a record number of MLS teams to the quarterfinals in 2012, Major League Soccer is going to have to work hard to avoid seeing three of five teams eliminated. We might even wind up with a situation where only one MLS team is left standing after the group stages.

This week's slate of group stage matches will go a long way in determining the fate of LA Galaxy, FC Dallas, Colorado Rapids and Toronto FC. The Seattle Sounders are the only MLS team in comfortable position to advance, but even Sigi Schmid's side has some work to do before securing safe passage to the second round.

So how did things fall apart so quickly for an MLS contingent that was unbeaten against the rest of the field after two rounds of group play?

Galaxy return to Earth

You can start with the Los Angeles Galaxy, which opened group play with a pair of impressive 2-0 home wins and looked like a team that would stroll to the quarterfinals. That all changed in Mexico, when LA saw a 1-0 lead vanish amid some questionable calls in an eventual 2-1 loss to Morelia.

Rather than rebound, the Galaxy traveled to Costa Rica and dropped a 1-0 loss to Alajuelense, a deflating defeat made worse by the fact LA fielded close to a full-strength squad.

The two losses, coupled with Morelia and Alajuelense taking turns battering Honduran side Motagua has left the Galaxy in third place in Group A, facing the unenviable task of needing wins in each of their two remaining matches to secure a place in the quarterfinals.

Now, the Galaxy's fate will be determined in a difficult match-up on Wednesday against Morelia at Home Depot Center - a match the Galaxy will need to win without David Beckham, who is suspended due to yellow cards. LA's home-field advantage will also be restricted as limitations on attendance at mid-week matches at Home Depot Center (which is located on the campus of Cal-State Dominguez Hills) means the stadium will only feature approximately 10,000 fans.

No fear of calm Rapids

For the Colorado Rapids, the opening group stage victory against CD Metapan raised red flags about the team's realistic chances of success in the Champions League. It took some very questionable calls going their way for them to squeeze out a home win, then Gary Smith fielded a reserve side against reserve size cellar dweller Real Espana. The subsequent draw left the Rapids on unsure footing.

Then the Rapids really hit bottom. An embarrassing 4-1 mauling by Santos Laguna at Dick's Sporting Goods Park exposed Colorado, but an even more troubling 2-1 home loss to Real Espana followed, leaving the Rapids in last place in Group B.

Now, with two road games remaining in the group, and the Rapids mired in a five-match winless streak in league play that's suddenly put Colorado's playoff position in jeopardy, the Rapids may have no choice but to basically give up any real hope of advancing out of Champions League group play.

Two teams enter ...

FC Dallas and Toronto FC find themselves in the position of battling each other for a place in the quarterfinals. With UNAM Pumas expected to dispose of Tauro FC in the final Group C match, Toronto FC will need to beat Pumas at BMO Field on Tuesday to set up a winner-take-all match-up against FC Dallas at Pizza Hut Park on Oct. 18. That's assuming FC Dallas can travel to Panama and secure a result against Tauro FC.

Seemingly sure thing

The easiest road any MLS team has is Seattle, and even the Sounders aren't assured of a place in the quarterfinals. Seattle leads Group D right now with nine points, but a road trip to take on Guatemala's Comunicaciones on Tuesday night won't be easy, and the final group stage match will come against Champions League holders Monterrey at CenturyLink Field on Oct. 18th.

The Sounders need a point from one of those remaining matches to secure safe passage to the knockout rounds, but with playmaker Mauro Rosales sidelined, Seattle could wind up sweating out the final match day if it loses its remaining two matches.

Best, worst case scenarios

The best case scenario for MLS will be to see Seattle, Los Angeles and FC Dallas progress to the knockout rounds in 2012. They happen to be three of the four best teams in MLS (with Real Salt Lake being the fourth), and they each boast the kind of depth to do damage in the knockout rounds. Throw in the fact the Sounders and FC Dallas could have Steve Zakuani and David Ferreira back from lengthy injury absences and the chances would be good that at least one MLS team could put together a run to the final like Real Salt Lake did last spring.

And the worst case scenario? The Galaxy, Sounders and FC Dallas all falter and fail to advance, the Rapids fold as expected, and Toronto FC is left as the last team standing. It would mean an impressive turnaround for the Canadian club, but would leave MLS with no American teams in the knockout rounds, and a TFC team that would find it difficult making much of a run without more roster improvements in the winter.

That nightmare scenario was unfathomable just two weeks ago, but the CONCACAF Champions League has reminded MLS that it is an extremely tough competition, and MLS teams are going to have to do much better if they are going to make this installment of the tournament one to remember, or one for MLS fans to forget.