LAFAYETTE — Chris Masson had no idea that he would go from pre-game backup to a history-making quarterback in a performance that he could only describe as amazing.

Masson, a two-year starter, replaced injured starter Blaine Gautier early in the first quarter and then led the University of Louisiana at Lafayette to a 31-17 victory over perennial Sun Belt Conference leader Troy Saturday night before 29,775 at Cajun Field. It was the sixth largest crowd in school history.

Along the way, Masson threw for 211 yards and two touchdowns, vaulting to a fourth place tie on the school’s all-time list for touchdown passes and fifth place in career passing yards.

For Masson, who lost the starting job to Gautier two games ago, it was night he will never forget.

“This is amazing. We have never beaten (Troy) in the five years I’ve been here, but with the large crowd we had here, beating them at home and stepping in like I did, it’s all amazing,” Masson said.

Masson said his weeklong preparations included the idea that he had to be ready if necessary to replace Gautier, who left the game during ULL’s first offensive possession.

“That’s the role of the backup quarterback; you’ve got to be prepared for any moment and that’s what happened,” he said.

The Cajuns’ win, the first over Troy since 2005, propelled them to 5-1 and kept them in first place in the SBC at 3-0. The Trojans fell to 2-3 and 1-1 n the SBC.

ULL coach Mark Hudspeth received a Gatorade bath following the victory, something which didn’t temper his enthusiasm for the way his team played.

“I don’t know what to say. I do feel that this team played outstanding in all three phases of the game,” Hudspeth said. “This is a big win for this program against a team that is year after year a power in our conference.”

Hudspeth praised Masson’s performance.

“That’s what our team is all about, preparing for stepping up when the guy in front of you goes down,” Hudspeth said.

Troy coach Larry Blakeney said his team got too far behind early against ULL, which took a 24-3 halftime lead.

“I thought (ULL) played extremely well,” Blakeney said. “They came out with a good plan and for us. It got to the point where we were behind and having to play a type of game that played into their hands.”

Eight of Masson’s completions went to wide receiver Javonne Lawson for 131 yards and a second-quarter touchdown.

Lawson said the victory was one that made a statement, especially to the rest of the SBC.

“It has to be,” Lawson said. “Troy’s been the big dog in this league and I think we showed tonight that things may be changing in this conference.”

In addition, the Cajuns got 81 rushing yards from freshman running back Alonzo Harris, who carried 22 times.

Troy quarterback Corey Robinson still threw for 322 yards and two touchdowns, completing 38-of-53 attempts.

Lawson felt the game change when ULL cornerback Melvin White intercepted a Robinson pass that White returned for an 89-yard touchdown.

White’s return was the longest by any ULL defensive back in the 41-year history of Cajun Field. The interception return with three seconds remaining provided the Cajuns with the final TD for their 21-point halftime lead.

The White TD ended a 17-0 run by ULL after Troy pulled to within four points (7-3) on a 36-yard field goal by Michael Taylor with 4:40 remaining in the first period.

At the time of the interception, the Trojans were traveling downfield on a drive that started at Troy’s 28 with 59 seconds left.

Gautier led the Cajuns’ first touchdown drive to open the game until he was injured with 12:41 left attempting to score on a 4-yard run.

With Masson in the game, ULL scored four plays later when he threw a 1-yard pass to freshman tight end Larry Pettis (10:32).

ULL scored its final 17 first-half points during the final 6:33 of the second quarter.

The Cajuns pulled in front (14-3) on a 79-yard drive that featured a pair of long completions to Harris and Green.

The touchdown reception came from 26 yards away when Masson threw to Lawson in the corner of the end zone. Lawson dragged a foot in order to stay inbounds.

On the next possession the Cajuns took a 17-3 lead on a 24-yard Baer field goal.

Griffin was the key weapon during the 49-yard field goal drive, gaining 10 yards in two carries and catching a pass out of the backfield from Masson for another 14 yards.

In the second half Troy took the kickoff and drove 80 yards in 14 plays to score on Robinson’s 6-yard pass to wide receiver Jaquon Robinson.

Later in the period the Cajuns scored their last points when ULL went 64 yards and scored on a 2-yard Harris run.

Harris had the key yardage, carrying for 22, but the key play came when the Trojans were called for pass interference on a Masson toss to tight end Ladarius Green.

The penalty gave ULL the ball at the Troy 16 and three plays later Harris was in the end zone.