ALLEN PARK -- Although injuries have not been used as an excuse for the Lions' 0-4 record, they have played a part.

Lions starting quarterback Matthew Stafford has missed the last three starts with a separated shoulder of his throwing arm. He said in a radio interview on Monday night that he is unsure if he will play this week.

“He will be back whether it’s this week or not, whether it’s next week or not, whether its the week after that it’s still yet to be determined,’’ coach Jim Schwartz said. “He’s doing a good job in his rehab, he’s right on course.’’

Wide receiver Nate Burleson, another key part of the offense, said on Monday that he ran routes and caught some balls on his own for the first time. He's given himself the green light to play on Sunday vs. the Rams. Of course, the trainers will get the final say.

“Probably Wednesday and Thursday will be big days for him and see what he’s able to do on the practice field and how much he can do. He’s a lot closer than he’s been the last couple weeks,’’ Schwartz said.

(Follow me on Twitter @PaulaPasche.)