Crockett, 34, worked out for Jon Gruden last week and is familiar with the coach's offense after playing for him in Oakland.

To make room on the roster, backup quarterback Chris Simms, slow to regain his form after missing most of last season following surgery to remove his spleen, was placed on injured reserve.

The Bucs lost Williams, the 2005 NFL offensive rookie of the year, to a season-ending knee injury two weeks ago. Pittman started last Sunday's game against Indianapolis, but was carted off during the second quarter with a badly sprained ankle that's expected to sideline him six to eight weeks.

With Williams and Pittman out, fourth-year pro Earnest Graham becomes the starting tailback. Rookie Kenneth Darby, a seventh-round draft pick who began the season on the practice squad, and Crockett will back him up.

Crockett has appeared in 174 games with the Colts, Raiders and Jacksonville Jaguars since entering the league as a third-round draft choice in 1995. He has 61 career starts and has rushed for 1,701 yards and 36 touchdowns.