"We played good team defense and were opportunistic early," said MSU head coach Tom Saxton. "We're very pleased because it was a great win in a tough environment."
Clem made six stops in the first half and then seven in the second, several of which came early in the frame.
"Courtney was very good tonight," said Saxton. "She maybe played the best game of her career to this point."
Fiebernitz, who converted on all three of her penalty kick attempts last season, wasted no time in rediscovering her form from 2013. An Aztec foul in the 11th minute gave the Spartans a penalty kick and Fiebernitz buried the ball in the back of the net to give MSU an early a 1-0 advantage.
Van Poppelen boosted the Spartan lead to 2-0 in the 29th minute. Allyson Krause picked up an assist on the goal.
"At that point it was a back and forth game and both teams had chances," Saxton said. "When we got the second goal it gave us a little momentum and maybe deflated them just a bit. It also allowed us to play little more conservative."
The Aztecs pressured the Spartans early in the second half, but Clem and Spartan defense stood strong to preserve the two-goal MSU advantage. In the 70th minute, Cheslik collected a loose ball and beat SDSU keeper Melanie Vaughn with a shot from 15 yards out for her first collegiate goal.
SDSU broke Clem's shutout bid when an MSU foul in the box led to an Aztec penalty kick in the 89th minute. Victoria Barba converted on the attempt, making the final score 3-1.
The Spartans will remain in California over the weekend, taking on Cal State Fullerton on Sunday at 7 p.m. ET.