Dayton (25-10), the 11th seed in the South Regional, advances to the regional semifinals next week and will play Kansas or Stanford.
The third-seeded Orange (28-6), who finished second in their first year in the Atlantic Coast Conference, struggled all game against the swarming Dayton defense, missing all 10 attempts from beyond the arc, while the Flyers hit seven times from long range.
After Sibert stepped out of bounds with 14 seconds left and Dayton up by one, Ennis took a jumper from just inside the 3-point line instead of driving the lane as he had all night.
The standout freshman finished with 19 points on 7-of-21 shooting, including 0-5 on 3-pointers.
Syracuse fouled Pierre and he made one free throw. Ennis rushed down court and missed the potentially winning 3 as the buzzer sounded.
Sibert finished with 10 points and Sanford had eight.
It was another close win for Dayton after beating in-state rival Ohio State 60-59 Thursday. After that game, the Dayton Daily News mocked Buckeye fans who refer to "The Ohio State University" with a headline that read: "THE University of Dayton."
Florida 61, Pittsbugh 45 • In Orlando, Fla., Scottie Wilbekin sat on the bench for the final minute, holding a bag of ice against his left knee.
It was about the only time he wasn't giving Pittsburgh huge problems on both ends of the court.
Wilbekin scored 21 points, including 11 of the team's 13 during a 7-minute stretch in the second half, and top-seeded Florida handled the Panthers. The Gators' 28th consecutive win put them in the Sweet 16 for the fourth consecutive year.
The latest victory followed a lackluster and head-scratching performance in the team's NCAA opener against Albany two days earlier.
The Gators vowed to play with more energy and intensity, and Wilbekin spearheaded the effort.
"We just wanted to come out and not let them play harder than us or not play as hard as we can," Wilbekin said. "I think we did a good job of having our energy up at the start of the game, and we played together on offense and played together on defense."
Wilbekin took over in the second half, scoring eight consecutive points at one point. Patric Young wasn't too shabby, either, finishing with seven points and eight rebounds. Will Yeguete added eight points all in the paint.