Butler (17-4, 4-2) was led by senior guard Rotnei Clarke's 17 points. He shot 3-for-7 from 3-point range, but was pressured by the athletic Saint Louis guards all night.
Senior Andrew Smith added 12 points and six rebounds. Freshman Kellen Dunham led the Bulldogs on the glass, grabbing a career-high seven rebounds.
The Billikens used pressure defense to force Butler into a season-high 23 turnovers.
The Bulldogs had committed 12 turnovers in the first 12:12 of the evening, but still trailed just 14-12 at that point. A lay-up by sophomore Roosevelt Jones at the 6:28 cut the SLU lead to 17-14, but the Billikens then ripped off a 14-0 run. Butler answered with a 9-0 run over a span of 67 seconds to pull within 31-23, but Jordair Jett made a 3-pointer as the first half ended to give SLU a 34-23 lead.
Saint Louis picked up where it left off in the second half, starting with a 9-2 run to run ahead 43-25. Later, a pair of Clarke free throws at the 14:46 mark cut the Billikens' lead to 45-33. That's the closest Butler would come in the second half. Saint Louis would go on to grow the lead to as much as 71-51 late in the game.
Saint Louis (15-5, 4-2) was led by Jett, who scored 19 points on 8-for-12 shooting. Dwayne Evans scored 15 points on 6-for-8 shooting and Rob Loe added 12. The Billikens pounded the ball inside for a 51-22 scoring advantage in the paint and also had a 19-2 edge in fast-break points.
The one area where Butler excelled was rebounding, as the Bulldogs held a 37-29 edge on the boards. Butler had eight offensive rebounds and held Saint Louis to five.
The Bulldogs will host Rhode Island Saturday at 4 p.m. (CBS Sports Network).