Shields breaks up a pass to Pierre Garcon in Thursday's game

Undrafted free agent cornerback Sam Shields looks like he’s just about locked up a roster spot on the Green Bay Packers.

Pat Lee, a former second-round pick, looks like he’s in danger of getting cut.

Shields served as the Packers nickel cornerback during Sunday’s practice. While some sources have suggested he could soon be taking over that role, that doesn’t appear to be entirely accurate. Brandon Underwood, who’s served as the nickel back since camp opened, suffered a shoulder injury in Thursday night’s game and didn’t practice on Sunday. It’s unclear how long Underwood will be out.

Shields’ elevation does however signal impending doom for Lee.

Lee opened camp as the dime back, but when you take into account the fact Shields played more with the No. 1 defense on Thursday and today’s practice, it’s clear Lee has been surpassed by Shields.

Lee played with the third string defense on Sunday, along with D.J. Clark. Shields and Jarrett Bush, who is looking a lot like a cockroach these days, played with the No. 2 defense.

Charles Woodson and Tramon Williams will line up as the starters when the Packers open at Philadelphia on Sept. 12. Either Underwood or Shields will be third, since Al Harris won’t be ready for the season opener.

Bush now looks to have an edge on Lee for what will be the final roster spot at cornerback, unless the Packers decide to put Harris on the physically unable to perform list. Harris would have to be far from returning in order for that to happen, since the Packers wouldn’t be able to activate him for the first six weeks of the season.

That scenario appears unlikely. Harris should be able to start practicing this week or next, meaning he’ll occupy a roster spot and either Lee or Bush will be released.