Junior center Erica Opdahl, battling illness, added 13 points and nine rebounds for UST. Senior forward Jessie Hays had eight points and three steals and sophomore guard Melissa Gotchnik had eight points and six rebounds.
The Tommies (9-12 overall, 7-10 MIAC) moved back into sixth place alone in the conference as St. Olaf lost to Gustavus to drop to 6-11. Bethel fell two games back (5-12) in the race for the sixth and final MIAC playoff spot.
Hays' 3-point basket with 8:56 to go gave the Toms the lead to stay. It was part of an 18-3 run that put St. Thomas ahead by nine points with 6:45 to go. UST made 9-of-9 at the foul line in the last 3:25.
Bethel has lost six in a row and nine of 10 since a Jan. 12 road win at St. Thomas. The Tommies are 4-4 in MIAC road games.
The Tommies have their final home game Saturday vs. St. Mary's (1 p.m.).