GLENDALE, Ariz. — The experts said UCF would need a miracle. In a season fueled by the miraculous, the Knights had no problem producing one more.

On the biggest stage in program history against the nation’s top-scoring offense in a game nobody expected they would win, the No. 15 Knights pulled off a 52-42 upset of No. 6 Baylor in the Fiesta Bowl late Wednesday night.

The Knights’ offense survived three first-half turnovers and traded punches with a team that set a NCAA record for most points in a 13-game season. The UCF defense, so maligned by talking heads, came up with multiple stops and crucial takeaways when needed most.

UCF, discarded by so many as the unworthy outsiders crashing the Bowl Championship Series party, showed they were more than capable of playing with the big boys.

The Knights, a 17-point underdog entering the game, ran the ball early and followed quarterback Blake Bortles late.

The offense put up more than 500 yards and its most-ever points against a ranked team, and showed they could pound the rock or beat the Bears through the air. Bortles threw two interceptions in the first half, but was efficient after halftime and passed for more than 300 yards and three touchdowns. Storm Johnson had yet another 100-plus yard outing on the ground and added three scores.

The defense, meanwhile, held its own against an offense that was averaging 53.3 points and 624.4 yards, keeping Baylor to one of its lowest point outputs of the season. Its secondary limited the big plays and the pass rush did enough to bother Bears’ quarterback Bryce Petty.

It was a dream start for the Knights, followed by the gritty, never-say-die second-half play that has come to define this team.

UCF took a 14-0 lead to start the game, then saw Baylor (11-2) fight its way back behind its high-powered offense. When the Bears tied the game at 28 in the third quarter, Bortles became the calm, clutch leader that has endeared him to teammates _ and to NFL scouts.

Bortles moved UCF right down the field for a third-quarter touchdown drive, connecting with Jeff Godfrey for a 38-yard gain and Breshad Perriman for a 10-yard touchdown. At the start of the fourth quarter with a chance to give the Knights a two-touchdown lead, he used his legs to deliver, rushing for 22 yards to set up his own 15-yard touchdown run.

When Baylor answered back to cut the lead to seven late in the fourth quarter, Johnson broke off a 40-yard touchdown run to provide enough cushion to last until the final whistle.

In front of an announced crowd of 65,172 at University of Phoenix Stadium, the Knights had confidence from the opening kickoff. UCF jumped to the early lead behind two Johnson rushing touchdowns. With the momentum building early for an upset, however, the Knights nearly threw it all away.

UCF (12-1) turned the ball over on three consecutive plays _ two Bortles interceptions and a Johnson fumble _ and that allowed Baylor to cut the lead to one. A muffed extra point was the only separation between the two teams, and had Petty not thrown an awful endzone interception to Brandon Alexander, it could have been worse.

That Baylor mistake allowed the Knights to regain their composure.

Bortles would hit junior Rannell Hall on two wide receiver screens, once to the left side and once to the right, and Hall would carry them 50- and 34-yards for touchdowns, showing off why his teammates call him “Speedy.”

In the second half, with Baylor threatening to spoil the party with its own miracle comeback, Bortles and the offense would once again find a way to lift the Knights to a win.

UCF coach George O’Leary said before the game it took years of work to help get the Knights to the biggest win in school history.

“There’s a lot of ways to do things,” O’Leary said. “I think as long as you stay in the trade, you continue on the same path that you started with, eventually you’re going to have the culture and program that you want. I think that’s what we have right now. We have the culture. We do well academically. We win at football.”

During a season that has been filled with program-defining wins, it was the final act in Arizona that will be remembered as the biggest win in UCF history.