ALLEN PARK, Mich. (AP) -- Jon Kitna knows his Detroit Lions played a terrible game on Sunday. In a way, he's happy about that.
"If we play a great game and we get beat, that means we aren't good enough," Kitna said Monday, a day after the Lions lost 56-21 in Philadelphia. "We know that isn't what happened yesterday. We didn't play well, and we can play better."
Coach Rod Marinelli agreed, but didn't want to dwell on the debacle that saw Philadelphia score six first-half touchdowns.
"Give credit to the Eagles -- they did a great job," he said. "Now we have to autograph that tape -- take full credit for the performance -- and send it to the rest of the league. And then it is over. We move on from here."
As usual, Marinelli talked mostly about fundamentals.
"We have to go back to the smallest things -- find the smallest detail that is lacking and hammer that," he said. "It is all about consistency with detail. It always is, all around the league. I know that it is hard to keep your nose to the grindstone 24-7 for 16 weeks, but the teams that can do that win a lot of games. I know that. I've seen it."
The Lions got through the first two weeks of the season in good physical shape, but weren't as fortunate in Philadelphia, especially on offense. Two key linemen, tackle Jeff Backus and guard Damien Woody, sustained rib injuries. Rookie wide receiver Calvin Johnson left the game after landing hard on his back and head while catching a pass.
Backus, normally one of Detroit's most durable players, was in obvious discomfort Monday. He sounded pessimistic about his availability for this weekend's game with Chicago.
"I know right now I'm really sore, and I don't know how it is going to react to treatment," he said. "I got kicked in the ribs last week, but this is a different injury. I felt something pop during pregame warmups, and it just got worse."
Backus second-guessed his attempt to play through the pain.
"I shouldn't have been out there," he said. "I won't be out there this week if I'm going to be a liability again. I was hurting the team, because I couldn't do my job."
Johnson and Woody were also in noticeable discomfort Monday, while linebacker Alex Lewis (hamstring) was getting treatment. Marinelli said he didn't have a clear idea whether any of them would play against the Bears.
"I guess I'd have to say they are day-to-day," he said. "They are all tough men, and they are willing to play with pain. But that's not the issue -- anyone can play with pain. You have to be able to play great football while feeling discomfortable."
NOTES: Kitna set a franchise record with 442 yards passing against the Eagles, breaking Charlie Batch's 2001 mark of 436. It was also a career high for Kitna, topping his 411-yard day for the Bengals against Philadelphia in 2001. ... RB Kevin Jones played a limited role in his first game back from a broken foot, carrying three times for five yards, but Marinelli said that was because of the lopsided score, not health reasons. "I felt good," agreed Jones on Monday. ... The Lions waived TE Rudy Sylvan, who had been activated from the practice squad on Sunday, and signed TE Courtney Anderson. Anderson had 25 catches for 285 yards and two touchdowns last season with Oakland.