CONCACAF Champions League quarterfinal preview: MLS vs. Liga MX

The 2015-16 CONCACAF Champions League returns this week, as the quarterfinal round commences with four Major League Soccer outfits pairing off against four Liga MX sides in the first legs of their home-away series.

MLS commissioner Don Garber has made no secret of his desire for one of his league's teams to win the Champions League crown, but with Mexico's foursome in form and MLS teams just rounding off their preseason, questions of fitness will surely be raised.

Here's a preview of all four first-leg quarterfinal fixtures:

Queretaro vs. D.C. United

D.C. United heads down to the Estadio La Corregidora, where Queretaro, last year's Clausura runners-up, await them. Former Real Salt Lake midfielder Luis Gil and ex-Vancouver Whitecaps star Camilo are but a few familiar faces in this Queretaro side.

D.C. United's main attacking threat, Fabian Espindola, won't have an easy go of it against Queretaro captain Miguel Angel Martinez, while Bobby Boswell and Steve Birnbaum will certainly be kept busy by Argentine striker Emanuel Villa.

Ben Olsen will hope his team can compete on a physical level against Queretaro, but he'll need new signing Luciano Acosta to perform in midfield if D.C. United is to grab a win away from home.

Seattle Sounders vs. Club America

The Seattle Sounders host Club America at a freshly revamped CenturyLink Field, and will do so without star striker Obafemi Martins, who departed the MLS club for a move to Chinese side Shanghai Shenhua.

Club America is, perhaps, Mexico's strongest team, and they're the reigning CONCACAF Champions League title-holders, having defeated the Montreal Impact in the 2014-15 final.

Sounders manager Sigi Schmid will have plenty of game tape to review ahead of this fixture. He'll be hoping his side can replicate Montreal's first-leg result from one year ago - a 1-1 draw away at the Estadio Azteca - while avoiding the Impact's mistakes in the return leg at Olympic Stadium, where Montreal collapsed to a 4-2 defeat, and 5-3 aggregate loss.

The atmosphere down at the Azteca is ever a fright, but Seattle's backed by 40,000 strong supporters who make sure CenturyLink Field isn't a quiet place to play, either.

Club America's Oribe Peralta is the main threat for Sounders defender Chad Marshall and goalkeeper Stefan Frei, while Pablo Aguilar will look to stave off Clint Dempsey on the flip side. The threat of multiple away goals in this first leg is a real danger for Seattle, so a touch of caution is probably necessary.

Tigres vs. Real Salt Lake

Real Salt Lake travels south of the border to the Estadio Universitario to take on Tigres UANL, the 2015 Apertura winners. Make no mistake about it: RSL's established defensive core, led by midfielder Kyle Beckerman, will have their hands full.

Tigres' main threat is French striker Andre Pierre Gignac, who has notched 20 goals in 29 appearances thus far with the club. Behind him, former Brazilian international Rafael Sobis pulls the strings, and with plenty of strength out wide, it's hard to see how RSL will be able to cope.

They'll need Javier Morales and Yura Movsisyan in tip-top form to get anything out of this first-leg fixture. As such, a 1-1 draw is probably a dream result for Jeff Cassar's side.

LA Galaxy vs. Club Santos Laguna

The LA Galaxy will likely take one look at Club Santos Laguna before pointing, gesturing, and perhaps uttering with confidence: "Bring it on."

Armed with new signings Nigel De Jong, Jelle Van Damme, and Ashley Cole, along with a core attacking trio of Steven Gerrard, Robbie Keane, and Mexican star Giovani Dos Santos, the Galaxy will be banking on the collective big-game experience of its stars in order to take home a big first-leg win at the StubHub Center.

They'll be going up against a cohesive Laguna team of 11 equal parts, with Chilean attacking midfielder Bryan Rabello the main threat to watch on the visitor's side. If any of the four MLS sides can pick up a big win in their first leg, it'd likely be Bruce Arena's LA Galaxy.