Mark Bergstrom had 15 points off the bench to lead the Oles (2-5 MIAC, 4-8).
Bryan Schnettler added 19 points, going 5-for-8 from the arc, for the first place Toms (6-1 MIAC, 9-3).
St. Olaf cut the Tommies' lead to 68-64 with 6:15 to play, but Rosefelt scored the next seven UST points and blocked a shot to seal the win.
Bobby Hunter added 12 points and Steve Banick and Chad Norberg each had 11 for the Oles, who have now lost six in a row.
St. Olaf had just 10 turnovers, but was 21-32 from the free throw line - including 11-of-18 in the first half.
The Oles will play at Gustavus Adolphus College on Wednesday at 8 p.m. The game can be heard via the St. Olaf Athletics Website.
UST 79, STOLAF 69 UST Isaac Rosefelt 10-14 5-5 25; Bryan Schnettler 7-12 0-0 19; Joey Shimek 2-5 4-6 8; Berker Tas 2-3 4-4 8; Sean Sweeney 2-8 1-3 6; Mike Keating 2-7 0-0 4; Nate Worrell 2-4 0-0 4; Danny Peterson 1-1 1-1 3; Lonnie Robinson 1-1 0-1 2; Alex Weaver 0-2 0-0 0. Totals 29-57 15-20 79. STOLAF Mark Bergstrom 4-6 5-5 15; Bobby Hunter 5-11 2-4 12; Chad Norberg 4-7 2-4 11; Steve Banick 5-7 0-0 11; Jon Bain 4-11 1-3 9; Mitch Haugen 0-1 5-8 5; Jon Butala 0-4 4-4 4; Brady McMahon 0-2 1-2 1; Robert McDonald 0-1 0-0 0. Totals 22-50 21-32 69. UST........................... 38 41 - 79 STOLAF........................ 39 30 - 69