Lining up for Green Bay on Thursday night at running back will be a combination of an undrafted free agent playing in his first NFL game (Don Jackson), a wide receiver who's chipping in to fill the void in the backfield (Ty Montgomery) and a veteran who's been in town for less than three days (Knile Davis). That's because the Packers placed starter Eddie Lacy on injured reserve, while backup James Starks is out about four weeks following knee surgery. Elsewhere on offense, tight end Jared Cook is still out with an ankle injury.