ALLEN PARK -- Injured Detroit Lions safety Louis Delmas is expected to be back for the start of the regular season according to a Detroit Free Press report.

On Wednesday, the team announced Delmas had undergone surgery on his left knee. The procedure was performed by renowned orthopedic surgeon Dr. James Andrews.

Following Wednesday's practice, Lions coach Jim Schwartz labeled the recovery process week-to-week.

"As soon as he is able to get out and go and keep it from getting sore, then he'll be back," Schwartz said. "The reason he ended up getting it done was an effort to be able to get back on the field."

Delmas had already missed the majority of training camp because of the knee. He tried to return last week, but left the field after working just a few snaps of seven-on-seven drills.

"At first it was sore, and then it was like, 'Okay, take a day off'," Schwartz said. "The next day it was still sore. Then he tried to go again. He tried to get back in, and we just weren't getting anywhere with it."

Delmas missed the final five games of the regular season in 2011 with a injury to his other knee. During that stretch the Lions' defense gave up 321 yards passing per game.

John Wendling and Erik Coleman are expected to start at safety for the Lions' preseason opener against the Cleveland Browns on Friday.