Seattle Sounders and FC Dallas cut the gap to just four points with LA Galaxy on the Western Conference table on the weekend.
The Sounders backed up their 4-2 victory over New York Red Bulls on Thursday by coming from behind to defeat New England Revolution 2-1 at CenturyLink Field.
Sainey Nyassi put the Revs ahead with a deflected shot from the edge of the area in just the third minute before Tyson Wahl hit back for the Sounders in the 34th with a brilliant free-kick from outside the box.
Alvaro Fernandez made it 2-1 just six minutes later when he finished from a tight angle after Mauro Rosales' through ball was knocked on by Roger Levesque to give the home side the win.
In Dallas, the home side produced a 4-0 victory over Portland Timbers thanks to goals from Zach Loyd, George John, Brek Shea and Jackson Goncalves to put last season's runners-up equal on points with Seattle and now just four in arrears of the Galaxy who were held to a scoreless draw by San Jose Earthquakes.
In the East, Philadelphia Union moved to the top with a hard fought 3-2 win over Chivas USA thanks to an 82nd minute winner from Danny Mwanga as the Red Bulls relinquished a lead to draw 1-1 with Chicago Fire to drop to second.
Elsewhere in MLS, Houston Dynamo scored a late leveler through Brian Ching to draw 2-2 at DC United, Sporting Kansas City beat Vancouver Whitecaps 2-1, Alvaro Saborio scored twice as Real Salt Lake defeated Toronto FC 3-1 as Columbus Crew had a big 4-1 win over ten-man Colorado Rapids.
2011 MLS season - Week 15 scores
DC United: 2 (Chris Pontius 31', Charlie Davies 73') Houston Dynamo: 2 (Brad Davis (p) 41', Brian Ching 89') RFK Stadium, Washington, DC - 15,734
San Jose Earthquakes: 0 LA Galaxy: 0 (red card: Josh Saunders 43') Buck Shaw Stadium, Santa Clara, CA - 10,872
Philadelphia Union: 3 (Veljko Paunovic 48', Carlos Ruiz 69', Danny Mwanga 82') Chivas USA: 2 (Michael Umana 28', Justin Braun 77') PPL Park, Chester, PA - 18,139
Sporting Kansas City: 2 (Omar Bravo (p) 33', Julio Cesar 40') Vancouver Whitecaps: 1 (Camilo Sanvezzo 15') LIVESTRONG Sporting Park, Kansas City, KS - 18,467
FC Dallas: 4 (Zach Loyd 34', George John 39', Brek Shea 58', Ruben Luna 87') Portland Timbers: 0 Pizza Hut Park, Dallas, TX - 10,470
Real Salt Lake: 3 (Nat Borchers 39', Alvaro Saborio 42'/60') Toronto FC: 1 (Maicon Santos 66') Rio Tinto Stadium, Sandy, UT - 15,077
Chicago Fire: 1 (Marco Pappa 58') New York Red Bulls: 1 (Joel Lindpere 40') Toyota Park, Bridgeview, IL - 16,961
Seattle Sounders: 2 (Tyson Wahl 34', Alvaro Fernandez 40') New England Revolution: 1 (Sainey Nyassi 3') CenturyLink Field, Seattle, WA - 36,212
Columbus Crew: 4 (Eddie Gaven 12', Andres Mendoza 18/48', Tommy Heinemann 57') Colorado Rapids: 1 (Conor Casey 5', red card: Conor Casey 29') Crew Stadium, Columbus, OH - 10,771