Kressel, the Bears' all-time home run leader, hit the first pitch from Mallory McKinney over the left field fence for her team-leading 11th home run of the year. She also tied the single-season home run record, which she set in 2005.
Senior Laurel Sagartz allowed three hits and struck out 11 as she improved to 25-1 on the mound. Sagartz picked up her 46th shutout of her career, moving into a tie for third on the all-time NCAA Division III list. She also moved into seventh place in Division III history with 853 career strikeouts.
Washington University, which won its 24th-straight game, advances to the winner's bracket final on Sunday at 5 p.m. (ET) against second-ranked Linfield College.
Sagartz and McKinney cruised through the first five innings without allowing a runner to advance past second base. The Bears had an opportunity to score in the bottom of the sixth with runners on second and third and two outs, but junior Amy Vukovich flied out to deep centerfield.
In the top of the seventh, UW-Eau Claire got back-to-back singles from Michelle Butkus and Jill Janke to start the inning. Junior first baseman Kaylyn Eash made a nice defensive play on a bunt attempt for the first out of the inning. Mandy Tschernach reached on an error to load the bases, but Sagartz got Bekki Kidnie to ground into a double play to end the threat.
Washington University (34-5) also threatened in the seventh as junior Karli Stander reached base for the third time on a bunt hit with one out. She stole second and advanced to third on a groundout, but junior Krista Swip struck out looking on a three-two pitch to end the inning.
Stander was 2-for-2 as the upped her team-leading batting average to .439. Janke had two hits to lead UW-Eau Claire, who dropped to 36-13 with the loss.