Sam Cronin scored for the second successive match for San Jose in the 14th minute to put his team in front. However, a Javier Morales penalty kick nine minutes before the break leveled the contest, with neither side able to snap the deadlock in the second 45 minutes.
Cronin scored a peach of a goal against Philadelphia last weekend and he found himself in the right place at the right time in the 14th minute when Chris Wondolowski worked himself free inside the penalty area and cut the ball back for Cronin to finish.
Morales came close 10 minutes later when his volley was cleared off the goal line, but San Jose gave away a penalty kick in the 34th minute when Jordan Stewart pulled down RSL's Olmes Garcia inside the box.
After stepping to the spot, Morales beat goalkeeper Jon Busch for his fourth successful penalty kick this season.
RSL goalkeeper Nick Rimando produced a fine stop on San Jose's Atiba Harris shortly before the break, while the best chance in the second half came in the 53rd minute as Salt Lake's Kyle Beckerman ripped a long-range shot just wide of the post.
The Earthquakes had one final chance in stoppage time when a cross from Cordell Cato was turned on goal by the head of Harris, forcing Rimando to tip the ball over the crossbar.