Memphis (3-2, 1-0 American Athletic) extended its best start in 10 years by taking advantage of a struggling defense and knocking Kiel out of the game on the final play of the first half. Linebacker Tank Jakes hit him in the lower right side as he threw a desperation pass.
X-rays were negative, but Kiel didn't return. Munchie Legaux took over in the second half as Memphis pulled away.
Cincinnati (2-2, 0-1) suffered its worst home loss since a 38-0 defeat to West Virginia on Nov. 9, 2005.
Lynch led an offense that piled up 610 yards. The second-year starter was 18 of 25 for 311 yards. He also ran 12 times for 45 yards. Sam Craft ran for 170 yards and a touchdown. Jake Elliott added a pair of field goals.
The Bearcats allowed 710 yards and an NCAA-record 45 first downs during a 50-28 loss at Ohio State a week ago and couldn't stop the Tigers, either, who were coming off a tough game. Memphis managed only 104 yards during a 24-3 loss at Mississippi.
Lynch got the Tigers going by completing his first five passes, including touchdowns of 9 and 29 yards. He also ran 10 yards on a draw play for another score as Memphis went up 27-7 at halftime.
His 10-yard touchdown run in the third quarter essentially put it away.
Kiel threw an 80-yard touchdown pass to Mekale McKay on the game's opening play, his 15th touchdown pass in four games. The Bearcats' offense then came apart. Kiel threw an interception and fumbled.
The Bearcats repeatedly dropped passes and couldn't get anything out of their running game, which was missing injured running back Tion Green. They also had Kiel's 6-yard touchdown pass late in the first half nullified by an offensive interference penalty.
Kiel was 11 of 27 for 216 yards with the two turnovers and two sacks. Legaux got his first significant playing time since returning from a gruesome injury to his left knee last season and completed 5 of 13 for 39 yards.
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