The first weekend of conference semifinal action across Major League Soccer determined very little and left us wanting more out of the four head-to-head clashes. 

Sunday's playoff quadruple-header should produce more excitement, along with the required clarity as four teams will move into the conference finals that begin after the November international break. 

The New York Red Bulls were the only road team to win the first leg, while Montreal and Seattle pulled off 2-1 wins over Columbus and FC Dallas respectively. Vancouver and Portland played to the only draw of the first-leg weekend, the Whitecaps and Timbers both failing to find the back of the net at Providence Park.

Now the focus shifts to the business end of the conference semifinals, which begin with one of the league's best rivalries at Red Bull Arena. 

The first match between the Red Bulls and D.C. United wasn't much of a contest. Jesse Marsch's men left with a one-goal advantage thanks to Dax McCarty's game-winning header in the second half. To make matters worse for the Black and Red, they failed to record a shot on target in the home defeat.

The good news for Ben Olsen's side is there is still plenty of time to make up for a match that many D.C. fans hope to forget sooner rather than later. D.C. must attack the vulnerable Red Bulls back four from the start of the match. In order to capitalize on the lack of depth in the home team's defense, Fabian Espindola and Alvaro Saborio must interchange well in the final third. Nick DeLeon must also try to exploit his mismatch against midfielder-turned-right back Sal Zizzo.

How the Red Bulls defense copes with the pressure and realignment after Damien Perrinelle's season-ending injury will be the deciding factor in Sunday's first match. Ronald Zubar, who some think should be suspended for the second leg because of an atrocious challenge in the first meeting, will partner the reliable Matt Miazga at center back. Kemar Lawrence should perform well at left back like he has all season, but Zizzo at right back is the weak link United must target. 

As for the Red Bulls attack, we expect the central-midfield trio of McCarty, Sacha Kljestan and Felipe to show up. The big question surrounding the Red Bulls moving forward is how much production they will get out of Bradley Wright-Phillips, who only had one shot on goal in the first leg.

Production from a top scorer who was mostly silent in the first leg is a major storyline for Columbus in Sunday's second match against Montreal. Columbus' leading scorer Kei Kamara was taken out of the first leg by the Impact center back duo of Laurent Ciman and Victor Cabrera. Donny Toia also limited the influence of Ethan Finlay on the right wing. Luckily for the Crew, Federico Higuain looked dangerous at Stade Saputo and finished a key away goal in the first half before Montreal struck twice. 

If the Crew can't get their attacking operation moving, they have to rely on their full backs to open up the wings moving forward and limit the opportunities the Impact receive on the counter. Harrison Afful and Waylon Francis may not be able to provide the scoring threat Finlay does, but they are capable of sending in quality deliveries into the box for Kamara to attempt to link up with.

Everyone will focus their attention on Didier Drogba in the Impact attack, and rightfully so, but Ignacio Piatti is the player who truly dictates how the club looks in the final third. If Piatti can stir up some chances early in the match, Montreal may be able to set the pace of the game at Mapfre Stadium. However, if Montreal concedes first, the match could end up wide open with the Impact needing to chase for an away goal.

FC Dallas will look to benefit from their away goal in the first leg on Sunday at home against Seattle in the third second-leg matchup of the weekend. Despite having the critical away goal in their pockets, Dallas must get going early and strike for a quick tally. That process seems simple with Fabian Castillo and Mauro Diaz driving the attack, but if one of the pair is shut down, the forwards, who haven't had a ton of success recently, must find spaces to create.

Just like Montreal, Seattle has big names at the top of its formation, but a pair of unlikely heroes may be the most valuable players for the Sounders in the second leg. Andreas Ivanschitz and Andy Rose have both made key contributions in the Sounders' two postseason wins thus far. Ivanschitz scored and impressed on the wing in the first leg of the conference semifinal, while Rose shut down Steven Gerrard and Juninho in the knockout-round win over the LA Galaxy.

If Sigi Schmid gets a true team performance out of his squad, Seattle will move a step closer to the winning its elusive first MLS Cup.

The fourth game on Sunday night might end up being the one that goes to extra time and even penalties. Vancouver and Portland enter BC Place scoreless, and given the way the first leg went, we could be in for a long night. Portland dominated the possession battle and the majority of the chances in the first leg, but it could not get a shot past the superb David Ousted. Vancouver had a few chances, but it wasted most of them, including Octavio Rivero's shot over the net in the first half. 

The X-factor in the Cascadia Cup clash will be the health of Pedro Morales. The dynamic Chilean, who is still working his way back to full strength, brings an extra gear to the Vancouver attack and takes the pressure off Kekuta Manneh and Rivero. Even if Morales comes off the bench in the second half, he may be able to give the Whitecaps the boost required to reach the Western Conference final. 

Since everyone loves making predictions, we'll take the Red Bulls and Impact in regulation in the East. The Sounders are our pick in the game between them and FC Dallas, while Vancouver should have enough to squeak past Portland, even if it takes extra time and one goal to do so.

Conference Semifinal 2nd-Leg Schedule (All Games on Sunday) 

D.C. United at New York Red Bulls (3 p.m. ET, ESPN)

Montreal Impact at Columbus Crew (5 p.m. ET, ESPN)

Seattle Sounders at FC Dallas (7:30 p.m. ET, Fox Sports 1)

Portland Timbers at Vancouver Whitecaps (10 p.m. ET, Fox Sports 1)

Players to Watch

Chris Rolfe, AM/FW, D.C. United

When D.C. United have needed a critical goal in the past two seasons, Chris Rolfe has usually been involved. The veteran attacker didn't create much in the first leg against the Red Bulls from the right wing because of the play of the Red Bulls' Lawrence and the inefficiency of the entire D.C. attack. 

Rolfe could line up at forward, but with United in need of an away goal early in the match, expect him to start on the wing again with Espindola and Saborio up top. 

If Rolfe can either create space between himself and Lawrence on the wing or cut inside and crowd the center of the pitch while working with the two forwards, D.C. should test Luis Robles early and often. 

Ethan Finlay, RM, Columbus Crew

When you record over 10 goals and assists in the regular season, you are expected to have the same production in the playoffs. That was far from the case for Finlay in the first leg against Montreal. 

In order for Columbus to dictate the match at Mapfre Stadium—and keep the ball off the feet of Piatti and Drogba—Finlay must become more involved. 

If he reverses his first-leg performance on Sunday, the Crew should have plenty of fun in the final third, with Finlay firing on all cylinders and opening up space for the other wingers and overlapping full backs. 

David Texeira, FW, FC Dallas

We all know what Castillo and Diaz are capable of in the FC Dallas attack, but in order to truly challenge Seattle for every minute of the showdown at Toyota Stadium, David Texeira has to be more visible in the final third. 

Texeira scored on three occasions in the final month of the regular season, but he was unable to carry that form into the first leg at CenturyLink Field, as he put just one shot on goal. 

If Texeira can break free from the Seattle center backs, he should be able to link up well with the young attacking duo. If that occurs, FC Dallas could earn revenge against the Sounders after falling to Seattle at this stage in 2014.

Matias Laba, CDM, Vancouver Whitecaps

An argument can be made that Matias Laba is the best pure defensive midfielder in MLS. Unfortunately, few people across the league have been able to witness his skills because of the lack of attention Vancouver received during the regular season.

The 23-year-old rarely makes a bad play and stops most of the attacks that come his way. Since the Whitecaps must keep Portland off the scoreboard, they will rely on Laba to disrupt Diego Valeri and Darlington Nagbe in the middle of the field. 

If the former Toronto FC man can keep the two dangerous Portland players out of a rhythm, the Whitecaps should hold the upper hand for the most of the match at BC Place. 

Joe Tansey covers MLS for Bleacher Report. You can follow him on Twitter, @JTansey90. 

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