For the first eight minutes of Saturday's game at Seiberling Gymnasium, Heidelberg was able to stay with the No. 2 team in the country.
The Student Princes came out against Mount Union with intensity, and grabbed a 14-13 lead when Paige Rickets connected on a jumper with 11:50 left in the first half.
But then the Purple Raiders heated up, Heidelberg cooled down, and Mount Union ran off with a convincing 84-63 victory.
After Ricketts' basket, the Purple Raiders went on an 18-2 run. Maggie Miller's trey with 4:38 left capped the stretch, and gave Mount Union a 31-16 edge.
"We couldn't score," said Heidelberg coach Marcie Alberts. "I knew coming into it we'd have to play, not a perfect game, but pretty close to it. You can't give a good team opportunities and second chances, and I think during that run we gave up a lot of second or third shots ... and then we weren't able to put the ball in the hoop ourselves."
Mount Union's effort was paced by Rosa LaMattina, who had six 3-pointers, a team-best six rebounds and 26 points.
"That's an All-American for you," Mount Union coach Suzy Venet said. "That's a senior who's focused and determined, and she made a bunch of big shots."
Mount Union also got a superb effort off the bench from Annie Bova, a freshman. Bova connected on four 3-pointers and had 16 points.
"Sometimes with freshmen it's up and down," Venet said. "It was pretty up for her in that second half."
Kathleen Phillips led Heidelberg with 18 points, while Rickets had 13 points and three steals. Megan Miller, a Columbian graduate, had 15 points.
Heidelberg dropped its third game in a row, falling to 3-3, 0-2 in the Ohio Athletic Conference.
"It's just a matter of getting that confidence back," Alberts said. "Winning makes you feel good about yourself, it goes a long way. When you're winning, shots seem to go down more often. We didn't make them today, and against a good team you've got to knock them down."
Mount Union improved to 7-0, 2-0 in the OAC.
Willard graduate Aly Daniel scored 10 points for the Raiders.