Junior Devin Buckley made 6-of-7 treys in the first half and closed with a game-high 29 points and the visiting Falcons (1-0) outscored St. Thomas 4-0 in the last 2:50 to hold off the host Tommies (0-1) at UST's Schoenecker Arena.
St. Thomas used a 34-14 second-half run to pull within five points at but couldn't get closer.
River Falls, 17-11 last season, shot 50 percent on the floor, outrebounded the hosts 38-33 and used a 12-5 edge in free-throw scoring. That offset its 10 second-half turnovers in the win. Brennan Witt came off the bench to chip in 10 points and 11 rebounds for UWRF.
Junior Michael Hannon came off the bench to score 16 of his team-high 18 points in the second half for the Tommies. Senior Grant Shaeffer had eight points and a career-best 12 assists; senior Jordan Burich added 14 points and six boards; and junior Ryan Boll had 10 points, seven rebounds and three steals.
UST shot just 25 percent in the first half (8-of-32) and trailed 45-22 at halftime. The Toms had only seven turnovers on the game and shot 51 percent in the second half (18-of-35).
UST pulled within 70-65 on Boll's jumper with 2:55 to go but didn't score on its next two possessions with a chance to pull within three. Buckley made 4-of-4 free throws in the final 40 seconds.