Davis severely injured his left ankle during Thursday night's scrimmage and was carted off the field in pain.

The UA, with Petrino unavailable to media, offered no comment on the injury Thursday night and did not offer specifics in Friday's release. Presumably the ankle was fractured given Davis will miss the season.

"I am extremely disappointed for Knile," Petrino said in Friday's release. "He is a captain who was incredibly focused on the upcoming year. His leadership throughout the off-season 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."

Juniors Dennis Johnson and Ronnie Wingo, both two-year lettermen, were in the rotation behind Davis but now become the feature backs.

The Razorbacks lost running back Broderick Green for the season with an injury during spring practice so true freshman tailback Kody Walker logged increased work in Thursday's scrimmage.

Davis, a two-year letterman from Missouri City, Texas, is eligible for a redshirt year to restore his junior eligibility in 2012.

A reserve in 2009 and at the outset of last season, Davis emerged in midseason of 2010 as the Hogs' feature back while rushing 1,322 yards, tops for SEC running backs last season. He rushed for 13 touchdowns and caught 19 passes for 136 yards and a TD.

The 6-0, 226-pounder rushed 100 yards or more six times last season and averaged 101 yards for the season despite netting just a combined 20 carries the first four games before starring in Arkansas' 10-3 campaign that ended with him netting 139 yards rushing on 26 carries against Ohio State in the Sugar Bowl.

Davis was on the preseason watch lists for the Doak Walker Award, (won twice by former Razorback All-American Darren McFadden), the Maxwell Award and Walter Camp Player of the Year Award.

In two seasons with the Razorbacks, Davis has gained 1,485 rushing yards and scored 17 TDs on 237 carries and caught 21 passes for 140 yards and one TD. He has appeared in all 26 games during his career with nine starts.

Davis piled up 1,322 rushing yards last season, the most by a running back in the SEC in 2010 and the fourth-highest single-season total in school history, and earned first-team All-SEC acclaim from the AP. His average of 6.48 yards per carry, the fifth-highest single-season average in UA history, led the nation among running backs with at least 200 carries, and his average of 101.7 rushing yards per game ranked second in the conference and 16th in the NCAA. He put together six 100-yard rushing games during the 2010 season, which tied for the fourth-highest single-season total in program history.