CINCINNATI -- In a matchup between the Atlantic 10 Conference's top two defensive teams, it was likely that defense would decide the outcome.
Even after 16th-ranked Saint Louis rallied to send the game into overtime, Xavier's defenders kept their clamps on Cody Ellis and the Billikens, allowing them just one field goal in OT while ending SLU's 11-game winning streak.
Freshman guard Semaj Christon scored 20 points and Travis Taylor added 19 points and a career-high 19 rebounds as Xavier denied Saint Louis a chance to earn both a share of the A-10 regular-season title and the top seed in the upcoming conference tournament with a 77-66 overtime victory at Cintas Center.
Saint Louis shot 1-for-11 in overtime, and Xavier made 14 of 16 free throw attempts in the extra five minutes to seal the victory.
"From the beginning of the game to the 45th minute, I thought we competed at both ends of the floor," Xavier coach Chris Mack said. "It says a lot about the character of our team, to do that against a team that I think is going to make a deep run in the postseason."
Brad Redford hit three 3-pointers and scored 11 points for Xavier (17-12, 9-6 A-10), which notched its second straight victory over a ranked opponent. The Billikens snapped then-No. 19 Memphis' 18-game winning streak on Feb. 26.
"We played with a sense of urgency on every possession tonight," Redford said. "We came out with a lot of energy. We didn't take anything for granted, even in overtime after they came back."
Kwamain Mitchell led Saint Louis (23-6, 12-3) with 17 points. Dwayne Evans added 16 points for the Billikens, who had their 11-game winning streak stopped, losing for the first time since Jan. 19.
Ellis, Saint Louis' second-leading scorer, went 0-for-15 from the floor, including 0-for-11 from 3-point range. He finished with five points.
"You think that's ever happened?" Saint Louis coach Jim Crews asked. "I kept telling him to shoot. The vast majority of his shots were good ones. It's a glaring stat, but it's not the reason we lost."
Mike McCall Jr. scored 14 points for the Billikens before fouling out with 1:28 left in overtime.
The Musketeers trailed by four points at halftime, but they roared back in the second half.
Taylor's offensive rebound and dunk put Xavier ahead 30-29.
"I tried to go after the ball every time it was in the air. I wanted to get them all," Taylor said of his career-best rebounding night.
A 3-pointer by Redford completed a 10-0 run, giving Xavier an eight-point lead. Another Redford 3-pointer put Xavier ahead 50-45 with 5:26 left.
The Billikens had just one field goal through the first 9:14 of the second half, but they rallied late.
McCall's fourth 3-pointer cut Saint Louis' deficit to 58-57 with 38.6 seconds left. Jordair Jett tipped in McCall's miss with 12 seconds left to send the game into overtime. Jett finished with 10 points and seven rebounds.
"We got down, but we kept fighting," Crews said. "I thought both teams battled."
Saint Louis, which leads the A-10 and ranks 19th nationally with an average of 57.9 points allowed, held Xavier to just 31 percent shooting in the first half.
The Musketeers wound up hitting 42.6 percent of their shots on the night, while the Billikens made just 30.1 percent.
Christon, who was 4-for-24 from 3-point range entering the game, hit a pair of 3s to tie the score 12-12. He had not made a 3-pointer since Feb. 9 at Duquesne.
Taylor scored six of Xavier's first 12 points, two on a dunk off an assist from Christon.
Xavier had just one field goal in more than six minutes in the first half.
McCall led Saint Louis with eight points in the first half, including two 3-pointers. Christon led all scorers with nine points before halftime.
"Xavier did a great job getting the ball to the basket," Crews said. "They're a strong team, a big team.
"I think the conference tournament is going to be wide open. It's a great year for the league."
NOTES: The last time Saint Louis earned at least a share of a regular-season conference title was in 1970-71, when it tied for first in the Missouri Valley Conference. Its last outright regular-season conference title was an MVC crown in 1956-57. ... Saint Louis was ranked in the Top 25 for consecutive weeks for the first time since 1993-94. ... Last week, Christon earned A-10 rookie honors for the sixth time. Xavier's previous high for league rookie-of-the-week awards was three, shared by Stanley Burrell (2004-05), Lenny Brown (1995-96) and current Indiana Pacers forward David West (1999-2000).