The biggest rivalry in MLS takes center stage as Portland plays host to their arch rival, the Seattle Sounders in what's surely to be a testy affair for both sides. The Portland Timbers will look to suppress a dangerous Seattle attack, while Seattle will be fighting for any points in the Rose City as they battle for Western Conference supremacy. The last time these two sides met, Seattle came out on top 2-0 behind goals from Clint Dempsey and Marco Pappa. Check out the highlights below:

The Portland Timbers return home after a 1-1 tie at the New England Revolution, and a convincing 4-1 win against Alpha United in the CONCACAF Champions League. Most of the Timbers who will be featured in Sunday's game are the same ones who started against New England. After the game in Massachusetts, a mixed squad of players were flown to Guyana to compete in the Timbers first ever CCL match. Maxi Urruti and Fanendo Adi scored in opposite halves for the Timbers, and youngster Alvas Powell tallied on the 4th for the Timbers with just seven minutes to go. Coach Caleb Porter did well to balance the minutes of his attacking players; Rodney Wallace also getting some minutes when coming on for goal scorer Steve Zakuani in the 64th minute.

It's still not clear who coach Caleb Porter will favor at forward, but you can be sure his midfield will remain the same. Porter let most of his starters from August 16th's battle against the Revolution return to Portland to focus their attention on this Sunday. Timbers fan are expecting another big game from the midfield maestro, Diego Valeri, who has been in spectacular form lately. Valeri currently leads the team in assists (8) and sits second in goals (7) behind Maxi Urruti. The Timbers couldn't get much going in their last bout with Seattle, a 2-0 Sounders victory, with a lineup that included former Seattle Sounder Steve Zakuani up top, Jack Jewsbury, in the midfield, and Raushawn McKenzie playing center back. This time around, Porter should field a team with at least two different players if we assume he continues to use the back four of Harrington, Ridgewell, Paparatto, and O'Rourke. Neither of those four were in the 18 man squad in Guyana.

If the Timbers want to take points from the Seattle Sounders, they'll have to do so by repelling the attack put out by Clint Dempsey and Obafemi Martins. Martins threatened the Earthquakes goal on Wednesday, and provided the assist for the Sounders' only goal in a 1-1 draw. Clint Dempsey started Wednesday's game on the bench and was subbed on for Brad Evans in the 78th minute, but was unable to rescue three points for his side. Seattle, much like Portland, is a team that is desperate for points. After jumping out to a commanding lead in the Western Conference and Supporter's Shield race this year, 2013 late season woes seem to be looming over Emerald City Supporters' heads; Seattle has gained one point in their last five games and now has four teams within three points of them in the Supporter's Shield standings.

In the last five matches between the Cascadian rivals, the Timbers are 3-1-1. 19 goals have been scored between Portland and Seattle in the last five matches, so expect both goalposts to see some action on Sunday. Like Caleb Porter and his attackers, Sigi Schmid is up in the air on who he will start in defense against Portland. The back four of Yedlin, Marshall, Scott, and Anibaba was able to conjure a shutout against the Timbers their last time out. Three of those four started for Schmid on Wednesday against the Earthquakes, Zach Scott excluded. Sounders fans have every bit of optimism that this is finally the game that Clint Dempsey finds his World Cup form. The last time Dempsey and the Sounders were in Portland, Clint scored two goals in his last five minutes to complete his hattrick and rescue a point for his side. Certainly Seattle will look to their captain to lead them on Sunday.

The Sounders will be hoping to leave their mark on Providence Park during the last match of the regular season between Portland and Seattle. The next chance the two teams have of meeting is in the MLS Cup playoffs, barring both teams make it. Last year the Timbers ousted Seattle from the playoffs after beating them 5-3 on aggregate. As it stands now, Seattle looks the more likely to be in the playoffs at the end of the year. They are currently tied for first in the Western Conference with Real Salt Lake on 42 points, but with a game in hand. The Timbers sit just below the Vancouver Whitecaps and the red line on 31 points with only 10 games left in the season.