PITTSFORD, N.Y. (AP) — Buffalo Bills running back Boobie Dixon could miss up to a month after pulling a calf muscle, posing a setback in his bid to secure a backup job.

Coach Rex Ryan provided the update Wednesday, when the Bills resumed practicing at training camp following a day off. Dixon was hurt Monday.

Ryan described the injury as "pretty substantial," and said the player could miss up to a month.

Dixon called the injury a "minor setback" in posting a note on his Twitter account Tuesday.

Dixon is a fifth-year player entering his second season with Buffalo. He was a dependable backup last year, when he had a career-best 432 yards rushing and a touchdown while filling in for injured starters Fred Jackson and C.J. Spiller.

This year, he's competing for a backup spot behind Jackson and newly acquired starter LeSean McCoy. Dixon is also a special teams regular, which provides him an edge in a competition that includes third-year player Bryce Brown and rookie fifth-round draft pick Karlos Williams.

Ryan also revealed that McCoy has been held out of team drills for the past two practices because of a sore toe.

He doesn't consider the injury serious, but said it's too early to determine whether McCoy will participate in a team scrimmage on Saturday.

Cyrus Kouandjio, who is competing for a starting job at right tackle, and backup defensive lineman Jarius Wynn were both sidelined by knee injuries on Wednesday. Ryan said the injuries do not appear to be severe.

Rookie tight end Chris Manhertz passed his physical and was activated from the active/physically unable to perform list.

___

AP NFL websites: http://www.pro32.ap.org and http://www.twitter.com/AP_NFL