Peruvian forward Ruidiaz gets 1st MLS goal, Sounders win
Seattle (6-9-5) is unbeaten in its last five games. San Jose (2-12-6) has gone 11 games without a win, including three straight losses.
Ruidiaz chested down a pass from Cristian Roldan near the penalty area on a breakaway and one-touched a shot inside the far post in the 62nd minute.
Ruidiaz, who signed as a designated player on June 29 after playing for Peru in the World Cup, also had two good scoring chances in the opening 20 minutes. Stefan Frei made five saves and recorded his third clean sheet in his last four games.