ORLANDO, Fla. -- Keyone Jenkins threw a 2-yard touchdown pass to tight end Grayson Brousseau in the second overtime, and UCF survived a wild finish in regulation to knock off No. 2 BYU 39-31 on Saturday.
Needing a touchdown and a 2-point conversion to force a third OT, the Cougars (6-1, 3-1 Big 12) drove to the UCF 4-yard line, but Bear Bachmeier's fourth-down pass to Walker Lyons fell incomplete, giving the Knights (4-3, 2-2) their first win over a top-five team in school history.
A week after knocking off then-No. 2 Notre Dame, BYU became the latest unbeaten team to fall in a wild few weeks of the college football season.
UCF was driving toward a potential winning field goal in regulation when Jenkins lost the ball on a play that was ruled a sack on the field. But after a replay review, the call was overturned to an incomplete pass, and BYU was flagged for unsportsmanlike conduct, moving the Knights into kicker Will Stone's range.
But BYU blocked Stone's 47-yard attempt to force OT.
Jenkins finished 25-of-41 for 293 yards and three touchdowns and ran for a score in his fifth start since replacing Alonza Barnett III, who is sidelined with a hamstring injury.
"There's a lot of teams in football with their quarterbacks hurt and their backups aren't doing great," UCF coach Scott Frost said. "Our backup is not a backup. He had an unbelievable game tonight."
Tyren Hornes had six catches for 137 yards for the Knights, and Duke Watson ran for 94 yards on 15 carries.
Bachmeier threw for 257 yards and two touchdowns with one interception. Kyler Kasper had six catches for 129 yards.
The Knights drove to the BYU 1-yard line with less than two minutes left in regulation, but Jenkins was stopped on a quarterback sneak on fourth-and-goal.
"That's the weirdest end of a game I have ever seen," Frost said. "I thought it would take 31 to win it. It should have if we would have got a sneak in."
UCF forced a three-and-out and got the ball back with 42 seconds left but couldn't convert the game-winning kick.
In the first overtime, Bachmeier gave BYU the lead when he connected with Legend Glasker for a 28-yard touchdown, and UCF tied it on a single play when Jenkins hit Josh Derry for a 25-yard TD.
There were five lead changes in regulation. Jenkins' 1-yard touchdown run late in the third quarter put UCF ahead 24-21, and BYU's Matthias Dunn connected on a 47-yard field goal early in the fourth quarter to tie it at 24-all.