Once again, the offense fell asleep in the second half. Once again, the opponent had claimed momentum.

Yet somehow, in the fourth quarter of a pivotal, tense, 23-20 loss to Prairie View inside A.W. Mumford Stadium, the Southern football team found itself right where it wanted to be — with the football in the fourth quarter, with a chance to drive for the game-winning score.

Once again, just as quickly, it all fell apart.

With 5:23 remaining in this Southwestern Athletic Conference showdown, Prairie View forced a fumble recovered a fumble by SU quarterback Dray Joseph, then drained the clock and got a 19-yard field goal from Christopher Barrick with 10 seconds remaining, allowing the Panthers to escape Baton Rouge with a suddenly firm grip on first place in the Western Division.

It was the third time in less than a month Southern had a chance to win in the fourth quarter but blew it.

On Sept. 17, the Jaguars gave up a fourth-quarter touchdown and lost to Jackson State by four points.

A week later, they had a 16-point second-half lead against Florida A&M, then gave it away and lost by five points.

Then there was Saturday.

“That was probably the toughest loss I’ve had in two years,” second-year coach Stump Mitchell said.

It was easy to understand why.

Southern’s defense largely held its own against Prairie View, which came into Saturday’s game with a potent offense that averaged 30.8 points per game. The Panthers managed only 258 yards from scrimmage against SU.

But the Jaguars offense struggled in the second half, looking out of sync after it switched from Joseph to freshman quarterback J.P. Douglas. Although tailback Sylvester Nzekwe finished with 108 rushing yards and the Southern offense often looked sharp in the first half, the Jaguars managed only 99 yards after halftime.

Southern’s only second-half touchdown came when linebacker Anthony Balancier picked off a pass and returned it 38 yards, tying the score at 20-20 late in the third quarter.

It was still tied late in the game when SU (2-4, 2-2) took over at its own 36-yard line. By then, Joseph was back in the huddle (Douglas played the entire third quarter, completing 2 of 8 passes; Joseph finished 14-for-23 for 141 yards, two touchdowns and one interception).

On a second-and-8, Joseph, facing heavy pressure, stepped up in the pocket and took off. Before long, he met Prairie View linebacker Chris Townsend.

“I started to drop back ... and I saw the Southern quarterback come up,” Townsend said. “So I just came out of my break and tried to throw everything I had into him.”

Townsend heard the visitor’s sideline erupt. He didn’t know the ball was out. But his teammate, defensive back JohnMark Henderson, did.

“I had a hard block. I threw my man off, my linebacker made a good hit and I just ran to the ball,” Henderson said. “The coaches teach us (to) hustle, and hustle put me in the right spot.”

At first, Joseph appeared to be down. But television replays showed Joseph was on top of Henderson as he leaned forward, his knee never coming in contact with the grass.

Said Mitchell: “It appeared to be out. ... But I’m not going to question the officials. Not when I didn’t make some good calls.”

Prairie View (4-2, 4-1) took over on the SU 43-yard line with 5:23 remaining. And the Panthers offense burned valuable time off the clock. They converted a third-and-9 with a 9-yard throw from Jonathan Troast to Troy Minnick.

Then they ran five more times, reaching the 2 before they called for the game-winning field goal.

“Our offense did a good job,” Henderson said. “We practice that four-minute drill every day, and they did it to perfection.”

It made a winner out of first-year coach Heishma Northern, the former Glen Oaks standout and SU safety who’d spent the past six years as Prairie View’s defensive coordinator.

Northern also interviewed for the Southern coaching job in 2009. It went to Mitchell instead.

Saturday’s game also gave the Panthers their fifth win over SU in the past six meetings — a nearly unthinkable achievement just 10 years ago. The Jaguars had won every game in this series from 1972-2005.

Long before kickoff Saturday, the latest meeting looked like a good one. Prairie View rebounded from an embarrassing 63-14 loss to Bethune-Cookman in the season opener, winning three of its past four games to vault to the top of the Western Division.

Southern, on the other hand, had shaken off two tough losses and remained a half-game out of first place as the weekend began.

Now, the Jaguars are .500 in conference play, with a long road trip to Arkansas-Pine Bluff looming.

“That was a difficult loss,” Mitchell said. “To the fans, I feel sorry about. To the university, I feel sorry about. Because the guys are working hard.”

That was apparent in the first half, when Southern rebounded from a handful of early setbacks and put together its best drive of the season — a 15-play, 98-yard march that included everything the frustrated Jaguar Nation longed to see: strong runs, sharp passes, stunning catches and long third-down conversions.

Matt Hill’s extra-point attempt was blocked, however, and Prairie View kept a 14-13 lead at halftime.

But the Jaguars offense had seemed to find a rhythm.

Just as quickly, in the second half, the Jaguars lost it.

Once again.