Englewood, CO -- (Sports Network) - Denver Broncos rookie running back Ryan Torain is expected to miss as much as three months after suffering ligament damage in his left elbow while practicing Wednesday.

"I was going to the ground and I put my left arm down to catch myself and I hyperextended my elbow and broke a bone," Torain said of suffering the injury in a blog on the Broncos website.

Torain, who was expected to challenge Selvin Young for a starting role in the Broncos backfield this season, will undergo surgery Friday.

A fifth-round selection out of Arizona State in the 2008 draft, Torain averaged 93.8 rushing yards per game and 5.4 yards per carry while posting seven 100-yard rushing performances in 19 career games (14 starts) during his two seasons with the Sun Devils after transferring from Butler Community College in El Dorado, Kansas.

"It's so frustrating because I just missed half of my senior season in college," Torain said. "Then I come back and I'm doing well in camp, about to play in my first game since October, and I injure my elbow and get sidetracked for three months."