MLS: Keys to Every Game on Matchday 3

Matchday 3 of the MLS season gets underway Friday with the Philadelphia Union taking on FC Dallas.

This will be followed by five games Saturday. The New England Revolution host the Montreal Impact, a team fresh off a 2-0 win against Alajuelense in the first leg of its CONCACAF Champions League tie.

Other marquee matches that day include Sporting Kansas City against the Portland Timbers at Sporting Park. The LA Galaxy welcome the Houston Dynamo to cap off the night.

The New York Red Bulls face their fierce rival D.C. United in the Red Bulls' home opener Sunday. The penultimate match of the weekend pits the San Jose Earthquakes against the Chicago Fire as they open Avaya Stadium in the Bay Area.

Here are the keys to every MLS match this weekend.

Philadelphia Union vs. FC Dallas: The Defense

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FC Dallas and the Philadelphia Union demonstrated their attacking prowess last week. For that reason, the defense for both teams will be crucial in this game.

The Union's attack will be weaker after midfielder Cristian Maidana suffered a knee injury in training, per Kevin Kinkead of CBS Philadelphia. Maidana will be out for two to four weeks.

However, the Union's Fernando Aristeguieta displayed his goalscoring prowess when he faced Real Salt Lake. He was gifted with a few opportunities, but he capitalized on two of them to score both of his goals.

It's vital that Dallas' center backs track the Venezuelan's runs. The absence of Maidana is huge, given his playmaking abilities, and it will make the Hoops' job a lot easier.

As for the Union, it won't be easy stopping Blas Perez, Fabien Castillo and the rest of the forwards corps. Philadelphia's holding midfielders Maurice Edu and Vincent Nogueira will have the task of shutting down the Dallas counterattacks.

New England Revolution vs. Montreal Impact: The Forwards

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The New England Revolution haven't scored in their two games, so far. The Montreal Impact also have failed to record a goal, but the team has only played one match. Something has to give Saturday afternoon.

Montreal's lack of scoring is down to the absence of a reliable striker. Jack McInerney may transform into a quality forward, but it will take time, especially with the squad turnover this winter and Justin Mapp's injury.

As for New England, Juan Agudelo hasn't scored in two appearances. On the other hand, he's returning from Europe where he seldom played competitive minutes, so he needs to readjust to his surroundings.

Revs head coach Jay Heaps may have to start Charlie Davies, if this dry streak continues. Davies notched four goals in his final five appearances last season. Surely, the 28-year-old can provide a scoring touch.

Both teams' back lines are still developing chemistry, especially Montreal's with the addition of Laurent Ciman and others. Given the lack of familiarity, either side can take advantage and finally get a goal.

Colorado Rapids vs. New York City FC: Counterattacks

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New York City FC exposed the New England Revolution last weekend with its pace. With forwards David Villa and Adam Nemec, NYCFC is a dangerous side when they break.

Meanwhile, the Colorado Rapids lost striker Deshorn Brown to Valerenga in Norway. This move has depleted an already thin forward corps for head coach Pablo Mastroeni.

The Rapids will most likely sit deep and let NYCFC have the ball. The high elevation is tough to deal with for visitors, so when New York pushes up, Colorado can quickly break out and counter.

Orlando City SC vs. Vancouver Whitecaps FC: The Playmakers

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Orlando City's Kaka and the Vancouver Whitecaps' Pedro Morales are the creative sparks for their respective sides, but as talented as they are, they can easily be nullified.

The Houston Dynamo were able to restrict Kaka's space in the last game. As a result, Orlando didn't generate a lot of scoring chances. This was mainly due to the team's insistence on playing through the center of the pitch.

Morales has had some moments of brilliance, too, but he's been hot and cold through two games. Toronto FC was able to close him down in the second half of the season opener. However, the Chilean recovered on the road in Chicago a week ago and produced one of his best away performances since joining MLS.

Both players are vital for their respective teams. However, it appears as if Kaka is being leaned on more by Orlando compared to Morales in Vancouver. If the playmakers struggle, it will be intriguing to see if either side tries to attack via the flanks.

Sporting Kansas City vs. Portland Timbers: Defensive Midfielders

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Through two games, it's glaringly obvious how much Sporting Kansas City need a defensive midfielder. Benny Feilhaber and Roger Espinoza are proactive and technical midfielders, but defensively, they're unreliable.

Paulo Nagamura, who started with Feilhaber and Espinoza against FC Dallas, failed to impress in the midfield. SKC's opponents Saturday, the Portland Timbers, will surely be just as lethal as the Hoops were a week ago.

Portland head coach Caleb Porter has switched to a more direct system this season. Given how quickly the Timbers can counter, SKC's Peter Vermes may have another tough game on his hands.

Dallas was able to expose the open space left by SKC's midfield, and Portland can do the same Saturday.

Houston Dynamo vs. LA Galaxy: Dynamo Attack

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The LA Galaxy can score goals, even when the attack isn't sharp. The Galaxy have recorded 22 shots in two games, but just nine attempts have reached the target, according to MLS' official website.

The Houston Dynamo have generated just 12 shots, three of which hit the target, according to MLS' official website. Houston has just one goal and seldom penetrated the Orlando City penalty area in its last game. 

In fact, the Dynamo have the fourth-lowest amount of shots in MLS this season, according to the league site. Giles Barnes and Brad Davis haven't been on the same page so far, while Oscar Boniek Garcia is still adjusting to a new role as a No. 10.

Dynamo head coach Owen Coyle is still feeling out MLS and his squad is still adjusting to life without Dominic Kinnear. However, if his team cannot create chances and score, LA will do this and hand Houston its second loss in as many games.

New York Red Bulls vs. D.C. United: The Coaches

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Both D.C. United and the New York Red Bulls will have depleted squads. The Red Bulls won't have full-back Roy Miller due to a knee injury and Ronald Zubar will most likely miss the match, according to the MLS website. Meanwhile, D.C. designated player Fabian Espindola continues to serve his six-game suspension.

D.C. also received horrible news about its other DP striker Eddie Johnson. The American forward has a heart condition that could end his career, Steven Goff of The Washington Post reported, and he'll most likely sit out this game. United head coach Ben Olsen may choose Chris Pontius and Jairo Arrieta to start up front as a result.

Red Bulls head coach Jesse Marsch also will have some decisions to make. Michael Lewis of Big Apple Soccer reported Marsch is hopeful that new signing Kemar Lawrence can start Sunday. If Zubar is deemed unfit, 20-year-old U.S. youth international Matt Miazga is tipped to replace him, according to MLSSoccer.com.

This will be a tactical battle with United's strong defense going against New York's solid attack. It will be intriguing to see how Marsch and Olsen tactically adjust during the game.

San Jose Earthquakes vs. Chicago Fire: Defending in the Box

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The Seattle Sounders FC proved to every MLS team that it's dangerous to give the San Jose Earthquakes' Chris Wondolowski space in the box. With playmakers, such as Matias Perez Garcia, and an equally capable goalscorer in Innocent Emeghara, it's risky to give any Earthquakes player space in the final third.

The same can be said about the Chicago Fire. Chicago hasn't scored yet, but it's down to individualism. Quincy Amarikwa, Harry Shipp and Shaun Maloney have been in the right spots, but they either blast a shot off target or hold onto the ball too long.

It's clear that the Fire miss Mike Magee, but the forwards have to shoot when they get in position. Chicago has just five shots on target this season, according to MLSSoccer.com. San Jose only has seven, but it has three more goals than its opposition. 

If Chicago cannot take advantage of its chances, it will be a long night for the Fire. Avaya Stadium will be rocking Sunday.

Peter Galindo covers MLS and U.S. soccer for Bleacher Report. Follow him on Twitter @GalindoPW.