Roberts scored 30 points and Dayton (No. 22 ESPN/USA Today, No. 17 AP) held off Saint Louis 68-57 in overtime on Saturday night for the Flyers' 13th straight victory.
The Flyers (14-1, 2-0 Atlantic 10) matched the best start in school history, which was last set during the 1955-56 season.
They received a major challenge from the Billikens (9-7, 0-2), who set a modern Division I record Thursday for fewest points in a game, falling 49-20 to George Washington. Saint Louis missed 23 consecutive shots at one point and finished 7-for-48 (14.6 percent) from the field, including 1-for-19 from 3-point range, in that game.
"We didn't know how [the Billikens] were going to come out," said Roberts, who scored seven of Dayton's 13 overtime points. "We didn't know if they were going to be down about that or if they were going to be fired up. We tried not to focus on how they were going to come out. We wanted to focus on how we came out."
The 13 straight wins is the second best mark in school history. Dayton won 19 consecutive games during the end of the 1967-68 season and the beginning of the 1968-69 season.
Luke Meyer led Saint Louis with 19 points, while Timmie Liddell added 18.
Charles Little had 16 points for the Flyers.
Dayton had a chance to win the game at the end of regulation, but Roberts' shot fell off the mark to send the game to overtime tied at 55.
"Saint Louis, they're a tough defensive team," Roberts said. "I knew it was going to be tough to get off a shot. I was kind of off-balance when I took the last one."
The Flyers scored the first six points of overtime, including four by Little to put the game away. The Billikens were 1-for-8 in the overtime session and only got a basket from Liddell with 44.8 seconds remaining.
"I feel bad for the guys who gave that kind of effort but just couldn't quite get it done," said Saint Louis coach Rick Majerus.
The Billikens surpassed the 20-point mark against Dayton at the 6-minute mark in the first half after their futile night at George Washington.
"That's as good a defensive team as there is around," Dayton coach Brian Gregory said of the Billikens. "You watch them on film, and you just wonder how you're going to score on them. ... These last 14 days, that's a team that is getting better. Throw that other game [Thursday] away because that was nothing."
The Flyers led most of the first half, but couldn't pull away from Saint Louis.
Kevin Lisch's 3-pointer from the top of the arc with two seconds left in the half tied the game at 30.