Defoe took Jonathan Osorio's through ball in his path and finished low past Stefan Frei to open his account after 17 minutes, then latched on to an errant pass from Sounders' Marco Pappa to bag his second seven minutes later. Clint Dempsey pulled one back for the hosts midway through the second half.
Matt Hedges netted a last-minute equaliser as FC Dallas claimed a 1-1 draw at Sporting Kansas City. Aurelien Collin broke the deadlock after 81 minutes but Hedges struck late on to ensure the 2013 champions remained winless from their opening two games.
A late double from Victor Bernardez saw the San Jose Earthquakes rally from two goals down to draw 3-3 with Real Salt Lake. Chris Wondolowski opened the scoring for San Jose in the seventh minute, but goals from Kyle Beckerman, Joao Plata and Luke Mulholland seemed to be sending them to defeat. Bernardez pulled one back in the 75th minute, though, then netted a leveller in the closing moments to salvage a point.
A goal from Thierry Henry was not enough to give the New York Red Bulls victory over the Colorado Rapids. The former France international opened the scoring in the 57th minute but substitute Vicente Sanchez levelled from the spot in the 72nd minute to ensure the match finished 1-1.
Sebastien Le Toux scored after 30 minutes to give the Philadelphia Union a 1-0 win over the New England Revolution, while Will Bruin's 40th-minute effort saw Houston overcome the Montreal Impact by the same scoreline and give the Dynamo their second victory from as many games.