Four-year veteran Mel Mitchell, who was expected to bolster New England Patriots special teams units weakened in free agency this spring and to add depth to the safety position, will undergo surgery next week for a torn biceps tendon sustained during Thursday's practice.

The injury will almost certainly sideline Mitchell for the 2006 season. The Patriots are expected to place him on the injured reserve list.

Mitchell, 27, signed a two-year contract with the Patriots as an unrestricted free agent in early April after spending the previous four seasons with the New Orleans Saints. The addition of the former Western Kentucky player came after the Patriots lost several key special teams performers, primary among them linebacker Matt Chatham.

Given the Pats' lack of depth in the interior secondary, there was a chance that Mitchell could have earned playing time from scrimmage in third-down situations.

A physical hitter with excellent size (6-foot-1, 220 pounds), Mitchell averaged more than 25 special teams tackles during the three seasons with the Saints in which he was healthy.

Two years ago, Mitchell posted a league-best 29 tackles on special teams and added two blocked punts and a touchdown (he recovered a blocked punt in the end zone). He has been less successful when playing from scrimmage, with only 45 career tackles on defense, but he does have skills that might have allowed him to play close to the line of scrimmage as an in-the-box safety in New England's scheme.

In 2003, Mitchell went to camp with the Saints projected as the starting strong safety, but then suffered a season-ending knee injury in the final preseason game.

It took Mitchell nearly two full seasons to recover from that injury, but until Thursday's injury, he had been healthy and playing well. Mitchell has appeared in 44 regular-season games.