Atwater stepped in front of Austin Davis's first pass of the drive that started with 1:19 left and no timeouts. Atwater crossed the field and raced into the end zone. He earlier recovered a fumble to set up the go-ahead score late in the third quarter.
Joe Webb rushed for 138 yards and a touchdown and passed for another score for the Blazers, who had lost three straight games and were humiliated 70-14 by the Golden Eagles last season.
Zahn hit a 51-yard field goal early in the fourth quarter and a 33-yarder with 1:27 left. The first kick was a yard shy of the school record accomplished three times.
The Golden Eagles made it 20-17 with Davis's 20-yard touchdown pass to Quentin Pierce with 5:24 left. Pierce had to reach back for the ball but side-stepped a diving defender on the third-and-18 play.
Davis completed six of seven passes for 70 yards on the drive, with the only miss coming when he was called for intentional grounding right before the score. He couldn't pull out another one at the end of a big night.
Davis was 24-of-32 passing for 234 yards with a couple of touchdowns to Pierce, who caught seven passes for 108 yards and his first two career scoring receptions. Davis completed his first nine passes but was sacked three times in the second half.
Fletcher's replacement Tory Harrison gained 66 yards on 11 carries.
The elusive Webb was a one-man show on UAB's offense at times. He ran 24 times against a defense that came in allowing a league-low 64 yards a game on the ground. Webb was only 6 of 13 passing for 23 yards--most of those on a 21-yard touchdown pass to Jeffery Andersonto make it 17-10 with 1:43 left in the third quarter.
Webb also scored on a 31-yard run that ended with him barreling through two defenders at the goal line in the first quarter for a 10-0 lead.
Southern Miss had botched a chance to jump ahead on the opening drive of the second half. The Golden Eagles lined up to go for it on fourth-and-1 from UAB's 25, but wound up punting because of a false start.
It was one of four Southern Miss drives to end without points in UAB territory.
The Golden Eagles had tied the game at 10-all at halftime when Justin Estes booted a career-best 49-yard field goal as time expired.