ORCHARD PARK, N.Y. — A week after being lured out of semiretirement, veteran quarterback Derek Anderson is going from mentoring Buffalo Bills rookie Josh Allen, to taking over the starting job for the injured player.

Coach Sean McDermott made the announcement Wednesday, when Buffalo returned to practice to prepare for its game at Indianapolis (1-5) on Sunday.

McDermott ruled out Allen because of a sprained elbow on his throwing arm. He said there's no plan at this point for the quarterback to have surgery.

McDermott also said a second medical opinion on the injury confirmed the initial diagnosis after the first-round pick was hurt in the third quarter of a 20-13 loss at Houston last week.

The injury leaves the Bills (2-4) turning to the 35-year-old Anderson preparing to make his first start in nearly two seasons. Anderson attempted just eight passes in three appearances as a backup in Carolina last year. He has a 20-27 record as a starter over a 12-year NFL career.

"He brings experience, leadership, presence to the table and he's worked hard the last week and a half here to get himself up to speed," McDermott said.

McDermott's only other option was turnover-prone backup Nathan Peterman, who lost the starting job to Allen after a 47-3 season-opening loss at Baltimore. The second-year player already has thrown four interceptions this season and 10 in seven games, including the playoffs.

Peterman's inexperience and struggles led to the Bills signing Anderson last week. Anderson was essentially out of football after completing his seventh season as Cam Newton's primary backup.

Though Anderson is new to Buffalo, the Bills are familiar with him.

McDermott was previously Carolina's defensive co-ordinator, while general manager Brandon Beane previously worked in the Panthers' front office.

Bills first-year offensive co-ordinator Brian Daboll held the same role in Cleveland in 2009, when Anderson went 3-4 in replacing Brady Quinn as the Browns starter.

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