COLLEGE STATION, Texas -- Trevor Knight probably experienced more than anyone could have expected in his Texas A&M debut Saturday afternoon.

Luckily for the Aggies, his experience is a plus.

The graduate transfer quarterback rode the emotional roller coaster in Texas A&M's 31-24 overtime upset of No. 16 UCLA at Kyle Field.

"That's a big-time win," Knight said. "First game for me in Kyle Field, it was special."

The wild season opener featured the underdog Aggies jumping out to a 24-9 lead and seemingly having the game under control in the fourth quarter, only to watch star Bruins quarterback Josh Rosen direct a furious rally that nearly ended with a win.

In the end, though, it was Knight who celebrated the win after his first start since 2014 with Oklahoma. He played sparingly for the Sooners last season before graduating early and landing in the lap of Aggies coach Kevin Sumlin.

Sumlin needed Knight after prized quarterbacks Kyle Allen and Kyler Murray left the program last December. The Aggies probably needed the stability and maturity Knight brings to the table as much as him arm.

The near meltdown in the fourth didn't faze the senior.

"He's an older guy and he was able to handle that," Sumlin said.

Knight accounted for three touchdowns, including the deciding score in OT, in leading the Aggies to a rare signature home win in the Sumlin era.

Knight's 1-yard keeper on fourth down in the first overtime session coupled with Rosen's final throw hitting the turf allowed the Aggies to escape.

Texas A&M (1-0) was just 1-7 against AP Top 25 teams at Kyle Field in Sumlin's first four seasons at the school. The Aggies doubled that win total by hanging on for dear life against a team expected to challenge for the Pac-12 title.

The Bruins (0-1) had been thoroughly dominated from the second quarter on before scoring two touchdowns, along with a two-point conversion, behind their sophomore signal caller in the last 4:19 of regulation.

Rosen's 62-yard touchdown pass to receiver Kenneth Walker with 2:39 remaining pulled the Bruins within 24-22. Rosen then found Austin Roberts to knot it at 24-all.

"What brought us back is just a will that we have, a determination that is developing, a belief in each other, a belief in what we are doing, a belief in the process that we've established," UCLA coach Jim Mora said. "We didn't look at the scoreboard."

Texas A&M had a chance at the end of regulation after safety Justin Evans snagged his second interception off Rosen with 37 seconds left, setting the Aggies up at their 46-yard line.

The Aggies couldn't get close enough to try a field goal, but Evans came up big again in overtime. His pass breakup on fourth down sealed the win.

Knight completed 22 of 42 passes for 239 yards, including a 40-yard touchdown to Josh Reynolds in the third quarter. The San Antonio native also scored twice on the ground, and he threw one interception.

"I thought he played unbelievable, especially with the adversity we faced," Aggies receiver Christian Kirk said.

Trayveon Williams led the Aggies with 94 yards rushing. Keith Ford, another Oklahoma transfer, ran for a touchdown and 64 yards. Kirk had eight catches for 58 yards.

Rosen (26 of 46 for 343 yards) made headlines leading up to the game by saying he wouldn't be intimidated by the atmosphere at Kyle Field. If the announced crowd of 100,443 didn't both him, Texas A&M defenders did.

Rosen rarely had time to set up and throw, especially as the game wore on. The Heisman Trophy hopeful threw three interceptions, was sacked five times and struggled to finish off scoring drives in the first half.

"He's going to shoulder all of the blame, but he was responsible for bringing us back as well," Mora said. "We've got to train him better at protecting the football and making better decisions. I didn't see him affected by the environment."

Soso Jamabo led the Bruins with 91 yards rushing on 23 attempts. Walker had six receptions for 115 yards.

The Aggies took a 10-9 advantage into halftime. Texas A&M took its first lead at 7-6 midway through the second quarter after Ford capped a 70-yard drive with a 7-yard run up the middle.

UCLA had its chances to score touchdowns in the first half, only to settle for JJ Molson field goals. Two long drives in the second quarter -- 93 and 69 yards, respectively -- stalled inside the Texas A&M 10-yard line.

The Bruins forced a turnover on the game's first possession, as defensive back Tahaan Goodman knocked the ball free from receiver Jamal Jeffery. Linebacker Kenny Young recovered it on the A&M 43-yard line.

UCLA could only manage a 38-yard field goal despite the good field position.

NOTES: Texas A&M opened at home against a nonconference ranked opponent for the first time since 1989 against LSU. ... The teams were meeting for the first time since the 1998 Cotton Bowl, with UCLA making its first visit to Kyle Field. A&M leads the series 3-2. ... In his fifth year at UCLA, coach Jim Mora dropped to 12-1 in nonconference regular-season games.