Argentine forward, Mauro Rosales, hopes to lead the Sounders past Monterrey's powerful attack. (Photo: Peter Aiken/Getty Images)

MLS teams started the new CONCACAF Champions League as well as anyone could have imagined, with a perfect 5-0 record and the first official win in Mexico in MLS history , but that perfect start won't matter much if the MLS contingent can't follow it up with a strong second week of Champions League action.

The Seattle Sounders will attempt to follow FC Dallas's lead by posting a rare win in Mexico when they take on defending Champions League winners Monterrey in Mexico tonight (live, 8 p.m. ET, FOX Soccer). The Sounders were impressive in their CCL debut, thrashing Guatemalan side Comunicaciones, 4-1, last week, but Monterrey will pose a much tougher threat.

Seattle will come in riding high after a hard-fought 1-0 win against FC Dallas , but it will be up to the Sounders defense to show it can deal with the potent Monterrey attack that helped the Mexican club lift the Champions League trophy in Utah in March.

Colorado also faces a difficult task with a trip to Honduras to take on Real Espana (live, 10 p.m. ET, FOX Soccer). The Rapids were very fortunate to escape their opening group stage match with a victory, coming back on two occasions and benefiting from a red card to Metapan on their way to a 3-2 victory. They'll now take on a Real Espana side that pushed Santos Laguna to the brink in Mexico before surrendering a late goal in a 3-2 loss.

Regardless of what Seattle and Colorado do tonight, Major League Soccer's perfect record in Champions League play will disappear on Wednesday when FC Dallas visits Toronto FC in their Group C tilt. Dallas should be riding high after knocking off UNAM Pumas in Mexico last week, but Schellas Hyndman's squad is faced with a defensive crisis as it copes with the impending transfer of George John and recent injury to Zach Loyd.

For Toronto FC, tonight's match is a chance to take control of the group and build on a recent surge in form that saw TFC go unbeaten in August before dropping a 2-0 decision in Chicago last Sunday. Aron Winter's side has shown improvement since the arrival of Designated Players Torsten Frings and Danny Koevermans as well as a series of trades that shook up the TFC roster.

With the second-worst record in MLS, TFC doesn't have much to play for in league and can focus solely on Champions League play in a way Dallas can't. That means trotting out the strongest possible lineup on Wednesday. A win would leave TFC in first place in the group, but a loss could hand control to Dallas and give UNAM Pumas a chance to recover and take its expected place in the top two in Group C.

The Los Angeles Galaxy can also take control of their group with a win at home against Costa Rican side Alajualense on Thursday. The Galaxy had no trouble disposing of Honduran side Motagua in last week's 2-0 opening win, but Alajualense impressed in a 1-0 victory against Morelia and will post a much tougher challenge.

The reigning Costa Rican champions will have the tough task of trying to stop newly-acquired Galaxy striker Robbie Keane, who is a safe bet to feature on Thursday after scoring in his Galaxy debut last Saturday.

A win on Thursday is vital because dropped points will only complicate matters in Group A, the toughest group on the competition.