COLUMBUS, Ohio (AP) -- Kwamain Mitchell looked pretty lucky when he banked in a 3-pointer to end the first half.
Turns out, he had plenty more in store.
Mitchell scored 22 points, including three big 3-pointers, and Saint Louis rode its gritty defense to a 61-54 victory over Memphis on Friday night in a West Regional second-round game.
Mitchell closed the first half by banking in a 3, then nailed two others to help the ninth-seeded Billikens (26-7) overturn an eight-point deficit in the second half. They advanced to play the winner of LIU Brooklyn and top-seeded Michigan State on Sunday.
Brian Conklin added 16 points, including five free throws in the final minute to salt the game away.
Will Barton had 16 points for the eighth-seeded Tigers (26-9), who had won 20 of their last 23 games.
The Billikens, making their seventh appearance in the NCAA tournament but first since 2000, have a team built around defense under coach Rick Majerus. They came in having held 10 opponents to 50 or fewer points and three under 40.
It was that defense that carried them in this one. They limited Memphis, a team averaging more than 75 points per game, to 39 percent shooting from the field. The Tigers were 2 of 15 from behind the 3-point arc.
Still, they led 37-29 with 11:51 left after point guard Joe Jackson scored on a 15-foot jumper.
Fighting and scratching on offense, the Billikens continued to turn the ball over against Memphis' own tenacious defense, but finally strung together five straight possessions that resulted in points to take command.
Mitchell banked in an off-balance 3 at the buzzer to pull Saint Louis into a halftime tie. With the Billikens trailing 42-40 and 6:24 left, he took an inbounds pass and swished a 3-pointer from the left corner for the lead.
After Memphis counterpunched on a bucket by Adonis Thomas, the Billikens tried to be patient in their halfcourt offense. Only Mitchell ended up trapped with the ball deep in his own backcourt with the shot clock ticking away. He took two dribbles and let fire with an extra-long 3 that found nothing but net. That bucket with 4:51 left put Saint Louis ahead for good at 48-44.
It also seemed to shock the Tigers.
Conklin, who hit 10 of 11 free throws, made two to make it 50-44. He hit two more a minute later for an eight-point lead with 3 minutes left.
The Tigers got as close as five but Conklin hit five free throws down the stretch and Jordair Jett added four more to maintain the lead.
The meeting was the 58th between the two old rivals, who used to spar in the Missouri Valley Conference, Metro Conference, Great Midwest and Conference USA.
Memphis, making its 24th NCAA tournament appearance, played in the 1973 and 2008 national championship games, falling to UCLA and Kansas, respectively.
The Tigers had won their last seven since a 60-58 loss at home that infuriated coach Josh Pastner and caused him to take their names off the backs of their jerseys and deprive them of hot food for a few days.
The Billikens, playing their set offense, shot 55 percent from the field in the second half and also hit 14 of 18 free throws to Memphis' 10 of 17.