Gunner Kiel threw a touchdown pass and ran for another score before hurting his ribs again, and Munchie Legaux took it from there Friday night, scoring a notable touchdown of his own while Cincinnati pulled away to a 34-17 victory over South Florida.

The Bearcats (4-3, 2-1 American Athletic) took advantage of the Bulls' many mistakes and got their second straight lopsided win. They also came away with more worries at quarterback.

Kiel has played the last five games with bruised ribs. He aggravated the injury on a scramble in the closing seconds of the first half, which finished with the Bearcats up 20-3.

The Bulls (3-5, 2-2) switched quarterbacks but couldn't pull off a second straight comeback. They had the biggest comeback in school history a week earlier, rallying from a 27-7 halftime deficit to a 38-30 win over Tulsa.

But now, USF is 5-15 in two seasons under coach Willie Taggart. Since starting the 2011 season with a win at Notre Dame and then three more victories against lesser teams, the Bulls are 9-31 under Skip Holtz and Taggart. That's by far the worst stretch in program history.

Legaux, who overcame a career-threatening knee injury early last season, had an emotional moment early in the fourth quarter. He ran 9 yards on his rebuilt left knee for his first touchdown since his comeback, slid on his knees at the back of the end zone and put his head on the ground, cradling the ball.

Legaux was 14 of 15 for 121 yards. Shaq Washington had a career-high 12 catches for 163 yards. He also had a 46-yard punt return — the longest by a Bearcat in five years — that set up a field goal in the first half.

Freshman Mike Boone ran 19 times for 212 yards and a touchdown, the first 200-yard game by a Bearcats running back in four years.

South Florida's Mike Wright had a rough time, going 11 of 19 for 92 yards with a pair of interceptions. He also lost two fumbles, the first of which set up a field goal.

Cincinnati's Rod Moore fumbled on Cincinnati's 12-yard line to open the second half, giving the Bulls a chance for a comeback. Wright fumbled the snap on the next play and was replaced by Steven Bench the next time the Bulls got the ball.

Bench had touchdown passes of 67 yards to 38 yards, taking advantage of botched coverages. He was 9 of 14 for 147 yards.

Cincinnati went ahead to stay on its opening possession, when Kiel hit Johnny Holton in stride on a slant and the receiver went all the way across the field for a 38-yard touchdown. Kiel also scored on a 17-yard draw play.

A defense that had been shredded in three consecutive games — a 50-28 loss to Ohio State, 41-14 loss to Memphis and 55-34 loss to Miami — showed improvement for the second straight game. The Bearcats were coming off a 41-3 win at Southern Methodist.

South Florida cornerback Chris Dunkley was ejected for a high hit on Washington shortly before halftime. Andre Davis — the Bulls' career receiving leader — was ejected for fighting midway through the fourth quarter.