The Tritons (1-0-1) had a number of opportunities to score in the first half, but took a 0-0 tie into the break. Less than seven minutes into the second half, dead-ball specialist Johnson found Wethe in the six-yard box, who placed the ball inside the left post with her forehead.
"We had created a number of chances in front of the net and finally we got a goal that turned out to be the game-winner," said UCSD head coach Brian McManus.
Three minutes later, Gabi Hernandez found an open McTigue at the edge of the box. McTigue, who fired a match-high five shots on the evening, placed the ball into the lower left corner for the final goal of the night.
The win over SPU (1-1-0) is UCSD's second in as many contests against the 10th-ranked team. The Tritons took down the Eagles 1-0 in the Sweet 16 of the 2010 NCAA Tournament. Earlier this week, UCSD tied Western Washington, 0-0, in Bellingham.
UCSD returns to action on Friday, September 9, when the Tritons will travel to Los Angeles to face No. 22 Cal State L.A. UCSD's first home contest is on September 25 against Cal State San Bernardino at noon.