He finished 17 of 35 for 206 yards, but also was intercepted once and sacked four times.
He knew he was in for a tough one when the first snap on BYU's initial possession scooted low past him. He scooped it up in the back of the end zone and was about to be tackled when Joe Kruger grabbed his face mask, voiding the safety and giving the Cougars a first down at the 20.
BYU punted six plays later and Charles Henderson's 57-yard return set up Hays' 17-yard touchdown pass to tight end Tonga, who made a one-handed grab over linebacker Kyle Van Noy.
Special teams continued to be game-changing, with Utah converting a fake punt on fourth-and-2 from its 24, only to see the drive end when Russell Tialavea blocked Coleman Petersen's 37-yard field goal attempt.
BYU's Sorensen, who had been injured throughout fall camp, was wide left on a 44-yard field goal attempt in the second quarter.
The Cougars finally got on the board with 4:40 left in the half on Nelson's 10-yard touchdown pass to Cody Hoffman, who extended his consecutive game streak with a catch to 22 games.
Hays was composed and tough, and his mobility helped.
He started 7 of 10 for 86 yards and a touchdown as BYU took the early lead, and kept another first-quarter drive alive with a 14-yard pass on third-and-11, and 14-yard pass on third-and-10.
The Utes were without starting free safety Eric Rowe because of a hamstring injury. And while running back John White insisted he would play, he did not play because of an ankle injury.
Top 25 Overview
It was over when... BYU missed two last-second field goal attempts, the second with no time left.
Gameball goes to... Jon Hays had two touchdown passes for Utah, which led after three quarters, 24-7.
Stat of the game... 14-0. BYU rallied furiously in the final quarter, outscoring Utah 14-0.