 Arkansas coach Bret Bielema talked repeatedly throughout the summer and preseason about how lucky the Razorbacks were to have such depth at running back entering this season.

That depth is about to be tested again following the announcement on Monday that freshman running back Rawleigh Williams is out for the season with a neck injury he suffered in a four-overtime, 54-46 win over Auburn.

Williams was injured in the third quarter and taken from the field on a stretcher. He had his facemask grabbed on the play before taking another hit from an Auburn player.

The freshman underwent surgery on Sunday, and Bielema said Williams was "upbeat" and expected to make a full recovery and possibly play football again — just not this season.

Bielema preferred not to describe Williams' injury in detail, but he did say how thankful he was for how quickly the medical personnel involved attended to Williams and kept the injury from being worse.

"Every report says that he's probably going to be able to play again," Bielema said. "It won't be until next year ... When you're talking about the severity and the injury that it is, there's a lot of time between now and then to figure out what he wants to do and what his family wants to do."

Williams has 254 yards rushing and a touchdown this season for Arkansas (3-4, 2-2 Southeastern Conference), which hosts Tennessee-Martin on Saturday.

He was forced into action earlier than expected when Razorbacks leading rusher from last season, Jonathan Williams, injured his left foot in a preseason scrimmage. Also, senior Kody Walker missed several games with a broken hand before returning with a cast in the win against Auburn.

Alex Collins leads Arkansas with 787 yards rushing this season, but it was Walker who was on the field for much of overtime against the Tigers — finishing with 32 yards rushing on eight carries, including a 4-yard touchdown run to force the fourth extra period.

Bielema said both running backs, and possibly others such as sophomore Denzell Evans and freshman Juan Day, will be needed moving forward to fill the loss of Rawleigh Williams, who was averaging 4.5 yards per carry.

"It's been unbelievable," Arkansas offensive coordinator Dan Enos said. "(Walker) and Alex are going to have to carry the load now, and thank goodness we had four (running backs) going into the season."

Bielema fought back tears on Monday while describing the moments after Williams' injury, particularly when he made eye contact in the stands with Williams' mother, Kim. She and Williams' father eventually made their way on to the field in Razorback Stadium while Williams was put on a stretcher and taken to a hospital.

"When one of your players tells you he can't feel his fingers, it's pretty freaky," Bielema said. "It's one of those moments where it wasn't anything more than just what was going on right there."