It only took one series of Saturday's preseason game against Cleveland to undo the good work.
DeAndre Levy, Detroit's starting middle linebacker, was seeing his first exhibition-game action because of a back injury, but pulled a groin muscle early in the victory over the Browns. He will at least miss Thursday's final preseason game.
"We know Levy isn't going to play against Buffalo," Schwartz said Monday. "We're going to get him some rest and try to get him back as quickly as possible."
Schwartz, though, acknowledged that there's a chance Levy won't be ready for the Sept. 12 regular-season opener in Chicago. Levy isn't sure.
"It is hard to say right now," he said. "It is going to depend on how it heals and how I feel next week."
The Lions have been decimated throughout camp by injuries at linebacker and in the secondary, but got a bit of good news on one of their key players. Safety Louis Delmas saw his first preseason action against the Browns and said Monday that he came out of the game in good shape.
"It felt good during the game, but I didn't know if that was just adrenaline in my veins," he said. "But it felt even better on Sunday and it still feels good today."
Delmas did not take part in Monday's practice, but Schwartz said that was a planned move.
Detroit also expects to get kicker Jason Hanson back against the Bills. Hanson, who had minor knee surgery early in camp, took part in warmups before the Cleveland game and kicked in practice on Monday.
"If he doesn't have any setbacks, I would anticipate that he'll be out there against the Bills," Schwartz said.
NOTES: The Lions signed LB Rocky Boiman and released three players: LB Lee Campbell, WR Eric Fowler and DE Chima Ihekwoaba. TE Jake Nordin was waived-injured. ... Detroit will practice against Tuesday, then have their preseason luncheon on Wednesday before hosting the Bills in the exhibition finale.