An Arkansas backfield that was once considered among the best in the Southeastern Conference is experiencing an unexpected bit of upheaval midway through the season.

The Razorbacks (3-4), led by the trio of Jonathan Williams, Alex Collins and Korliss Marshall, had the top rushing offense in the SEC as recently as a week ago. They fell to fourth with an average of 256.9 yards per game after a 126-yard rushing effort on 37 carries in a 45-32 loss to No. 9 Georgia.

The lack of output was notable because it was the second straight game Arkansas' power running attack — coach Bret Bielema's calling card since his arrival — struggled to establish itself. It did so with Marshall suspended and Collins suddenly mired in the worst two-game stretch of his career.

If the Razorbacks are to snap a three-game losing streak this week when they host Alabama-Birmingham (4-3) for homecoming, they will again have to do so without Marshall. Bielema didn't say what rule Marshall broke, but he is out for "about three to four weeks."

Marshall leads Arkansas in return yardage this season, including a 97-yard kickoff return for a touchdown against Northern Illinois. He has 116 yards rushing on 24 carries.

"He's only got one more opportunity to get it right," Bielema said. "If he doesn't get it right, it will probably be one of the saddest stories of my coaching career, because he's got a lot of talent and he's got a great heart. Just made some poor choices and those things won't be rewarded in our program, I guarantee you that."

While Marshall's status for the rest of the season remains uncertain, it' isn't nearly as confusing as what has happened to Collins.

The sophomore, who led Arkansas in rushing last season with 1,026 yards on his way to being named the SEC Freshman of the Year, has struggled mightily in the last two weeks — gaining a combined 43 yards on 17 carries in losses to Alabama and Georgia.

Collins was suspended for the first quarter of the loss to the Crimson Tide for missing a pair of workouts, and he has struggled since. He fumbled on his second carry of that game, and fumbled a toss from quarterback Brandon Allen against the Bulldogs, who scored a touchdown one play later.

Arkansas offensive coordinator Jim Chaney said part of Collins' lack of production against the Bulldogs was the result of a 38-6 halftime deficit, leading to 45 pass attempts for the Razorbacks. However, Collins' 2.5-yard per carry average over his last two games is a far cry from the 7.2-per attempt average he had before the Alabama game.

"Well, we will continue to try to get those up," Chaney said. "I don't know ... I would just as soon try to get him playing better all the time."

After leading the Razorbacks in rushing for much of the season, Collins is now second to the steady Williams. The junior topped the 100-yard mark for the third time this season against Georgia, finishing with 108 yards on 18 carries. He is averaging 96.7 yards rushing per game.

"The good news is J-Will remains consistently good at what he is doing," Bielema said.

Regardless of how the carries are split moving forward, Bielema knows Arkansas must find a way to again establish its run game if it hopes to snap a 16-game SEC losing streak in one of its four remaining conference games following Alabama-Birmingham.