The Pittsburgh Steelers will begin training camp practice Sunday without two key linemen and a second-round rookie corner.

Pro Bowl center Maurkice Pouncey (foot sprain), offensive tackle Mike Adams (back surgery), cornerback Senquez Golson (shoulder), backup quarterback Bruce Gradkowski (shoulder) and linebacker Shawn Lemon (Achilles) are on the physically unable to perform list. Adams, who is out about four weeks, is the only Steeler expected to miss significant time.

Golson's injury is one to watch. The Steelers want to see whether he can push for playing time at the slot corner position.

Adams isn't a starter, more of a swing tackle, so his absence doesn't hurt as much as Pouncey's, who should be back soon. But it does hurt. The team's No. 6 lineman missing an entire camp with a back issue is significant, especially because the line has battled injury issues over the year, forcing Adams to start four games in 2014.

Talented left tackle Kelvin Beachum is a free agent in a year. He just got more important since there's no solidified backup for him.