Arkansas coach Bobby Petrino confirmed Friday that running back Knile Davis is expected to miss the season because of a left ankle injury.

The injury is a major blow to the preseason expectations for the Razorbacks, who were 10-3 and reached their first BCS bowl game last season. Davis suffered the injury early in the scrimmage portion of practice on Thursday and was carted off the field without being able to put weight on his left leg.

"I am extremely disappointed for Knile," Petrino said in a statement. "He is a captain who was incredibly focused on the upcoming year. His leadership throughout the offseason was significant in the development of this team.

"Our athletic trainers and medical staff are the best in the country, and Knile's mental toughness will be an asset to him during the recovery process. I am fully confident in the mindset of our running back group and their ability to perform."

Davis led all Southeastern Conference running backs with 1,322 yards rushing last season, averaging 147 yards per game over the final seven games of the season.

He was a preseason second-team All-SEC selection and had also been named to the Doak Walker, Maxwell and Walter Camp Player of the Year award watch lists.

Ankle injuries are nothing new for Davis, the Missouri City, Texas, native who was limited to 33 carries for 278 yards after breaking an ankle his senior season in high school. Davis re-injured the same ankle during his first spring practice at Arkansas as a freshman, but surgery and rehabilitation appeared to have corrected the problem as he ran through SEC defenses during the second half of last season.

The Razorbacks likely will turn to some kind of combination of juniors Dennis Johnson and Ronnie Wingo to fill Davis' void at running back. Johnson averaged 9.2 yards per carry on just nine rushes last season before suffering a season-ending injury in the second game. He has averaged 6 yards per carry on 102 rushing attempts in his career and is also on the top kickoff returners in the SEC.

Wingo has rushed for 572 yards on 90 attempts (6.4 average) during his first two seasons, and he had 27 catches for 274 yards last season.

Arkansas' players weren't allowed to answer questions before the extent of Davis' injury was known following practice on Thursday. But junior quarterback Tyler Wilson briefly offered his thoughts on what to expect from the other running backs.

"I think they do a great job, no matter what the circumstances are," Wilson said. "They'll be all right."