STARKVILLE, Miss. — South Alabama quarterback Dallas Davis thought he’d be nervous before his first career start — against a Southeastern Conference opponent, no less — until he walked onto the field at Mississippi State.

He heard the deafening cowbells. He saw the big crowd. He knew his side was a huge underdog.

And somehow, he relaxed.

The Jaguars pulled the first major upset of the college football season, holding off Mississippi State 21-20 Saturday when Westin Graves’ 28-yard field goal try smacked off the upright and fell away in the final seconds.

Facing a team favored by four touchdowns, Davis capped a late comeback by throwing a 4-yard touchdown pass to Gerald Everett with 57 seconds left.

Davis, a 6-foot-2, 215-pound sophomore, completed 24 of 34 passes for 285 yards and two scores. He also had a highlight-reel run in the second half, hurdling Brandon Bryant on the way to another big gain.

The Jaguars took down an SEC team for the first time in school history. The players on this little-known Sun Belt Conference school down in Mobile will have quite a story to tell for the rest of their lives.

“I’m part of the South Alabama Jaguars,” beaming linebacker Roman Buchanan said, “that beat Mississippi State.”

Down 17-0 at halftime and still trailing 20-7 in the fourth quarter, South Alabama rallied with 99-yard and 71-yard touchdown drives.

“It was just coming out and playing better,” Davis said. “Ever since the beginning of camp, coach has preached playing fast and finishing strong. We didn’t start as fast as we wanted, but we dang sure finished strong.”

The Jaguars were in jeopardy of letting their lead get away until the very end.

Mississippi State drove down the field in the last minute and got in position for a field goal. But Graves’ kick hit the left post and dropped harmlessly to the turf at a stunned Davis Wade Stadium.

Most of the Mississippi State fans had long gone home on a hot afternoon and all that was left was a screaming contingent of a few hundred South Alabama fans. And, of course, dozens of jubilant South Alabama players.

It certainly was one of the worst losses in the eight-year tenure of Bulldogs coach Dan Mullen.

“We just didn’t execute real well at times,” he said. “And we had some absolutely critical errors. You can’t make critical errors and expect to win the game.”

Two days after Appalachian State — another Sun Belt program — almost toppled No. 9 Tennessee before losing in overtime, South Alabama kicked off a season that follows a year full of wild endings.

Multiple Jaguars said they weren’t surprised at the outcome — even if most everyone else was.

“They didn’t show us anything spectacular on film for us to change our gameplan,” Everett said. “So we just came out here and went at them 100 miles per hour.”

South Alabama coach Joey Jones said he was proud to give the Sun Belt a high-profile non-conference victory.

“To win a ballgame like this is a blessing,” Jones said.

Damian Williams finished with 143 yards passing and 93 yards rushing, including several impressive plays on the final drive for the Bulldogs. But it wasn’t enough.

MISSISSIPPI STATE’S QB SITUATION

Mississippi State came into preseason camp with a four-man quarterback race that was whittled to three in mid-August when Elijah Staley transferred. The Bulldogs started Nick Fitzgerald, but after two ineffective drives replaced him with Williams, who gave the offense some spark on the way to a 14-0 lead. Williams, however, wasn’t as effective in the second half until the final drive that ended with the missed field goal.

THE TAKEAWAY

South Alabama: It’s a massive win for the Jaguars, who lost badly to Mississippi State in both 2012 and 2014. The Jaguars were 0-4 against SEC opponents.

Mississippi State: This is undeniably a crushing loss for the Bulldogs. It also calls into question just how much Mississippi State will have in the post-Dak Prescott era.

UP NEXT

South Alabama: The Jaguars host Georgia Southern next Saturday in their first Sun Belt game of the season.

Mississippi State: The Bulldogs host South Carolina next Saturday in their first SEC game of the season.

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Follow David Brandt on Twitter: www.twitter.com/davidbrandtAP . AP College Football website: www.collegefootball.ap.org .