Servando Carrasco converted a penalty kick in the 70th minute, lifting the Sounders into a 2-2 tie.
Sanvezzo's goals in the 10th minute and the 26th were both assisted by Russell Teibert.
Timbers 2, Fire 2 • In Bridgeview, Ill., substitute Daniel Paladini scored on a 26-yard free kick in the 82nd minute to help the Chicago Fire to a 2-2 draw with the Portland Timbers on Saturday night.
Chicago (3-7-3, 12 points) also got an open-net goal from Mike Magee in the 68th minute in coming back from a 2-0 second-half deficit to extend its unbeaten run to three games. Portland (5-1-8, 23 points) stretched its unbeaten streak to 12 games, not having lost since a 2-1 decision to Montreal on March 9.
Timbers forward Diego Valeri scored in the 34th minute when his shot hit the left post and ricocheted right and past Fire goalkeeper Sean Johnson into the far corner. Portland also got a goal in the 58th minute when Ben Zemanski lined a 25-yard shot past Johnson.
Magee has two goals with the Fire and nine overall since being acquired last month in a trade with the Los Angeles Galaxy.
United 0, Revolution 0 • In Foxboro, Mass., the New England Revolution and D.C. United battled to a scoreless draw Saturday night in which Revolution goalkeeper Bobby Shuttleworth had to make just one save for his seventh shutout of the season.
New England (5-4-5) is unbeaten through its last five (3-0-2) matches and has lost just once in its last eight (4-1-3).
D.C. United (1-10-3) was shutout for the third straight match, for the eighth time overall this season and is winless in its last 12 (0-9-3) matches.
New England, which suffered three one-goal losses to D.C. United last season, saw its unscored upon streak stretch to 395 minutes.