ALLEN PARK, Mich. -- The Detroit Lions lost the quarterback of their secondary, leaving one of the team's weakest units from last season short-handed.
Safety Louis Delmas had surgery on his left knee Tuesday and will be evaluated weekly.
"As soon as he is able to get out and go and keep it from getting sore, then he'll be back," Detroit coach Jim Schwartz said Wednesday. "The reason he ended up getting it done was to get him back on the field. First it was sore, then he tried to go again, and we just weren't getting anywhere with it."
Delmas started the first 11 games of last season, but missed the final five after injuring his right knee -- that later needed surgery -- in a Thanksgiving loss to Green Bay. He had been icing left knee during training camp this year.
The four-year veteran started 30 of his first 32 games after Detroit selected him in the second round of the 2009 draft. He had not practiced in a week.
Without Delmas, the Lions allowed opponents to throw for 300 or more yards in three of their final five regular-season games, including Matt Flynn's 480-yard, six-touchdown performance in the last weekend. It was almost as bad in the opening round of the playoffs, when New Orleans' Drew Brees passed for 459 yards and three scores.
Amari Spievey, the other returning starting safety, said losing Delmas late last year hurt.
"He has a big impact on our defence. It was kind of difficult to get used to it without him in there," he said.
Spievey and nine-year veteran Erik Coleman, who played just four games last season, are the likely starters when the Lions (tied for No. 11 in the AP Pro32) face Cleveland on Friday night in the preseason opener.
"We've both got to be leaders out there now," Spievey said. "It hurts me a little bit because I love playing with (Delmas). His passion for the game is unmatchable. I'm going to miss him and hopefully he'll be back soon."
Schwartz would not elaborate on the surgical procedure, which was performed by Dr. James Andrews. He did the same when asked how long Delmas would be off the field.
"We really don't have any timetable," Schwartz said. "He's not day-to-day, he's more week-to-week."
Fans will see other new faces in the secondary Friday. Rookie Dwight Bentley, a third-round selection from Louisiana-Lafayette, worked opposite fellow cornerback Chris Houston with the first team most of the day Wednesday. Alphonso Smith, a projected starter, played most of his reps with the second unit.
Notes: RB Mikel Leshoure said he's making progress from a hamstring injury but still doesn't know when he'll be ready to fully participate in practice. Kevin Smith and Keiland Williams got most of the snaps with the first and second teams Wednesday. Michigan State men's basketball coach Tom Izzo and Detroit Police Chief Ralph Godbee watched practice from the sideline.