For Jahvid Best to return to the playing field this season, the Lions have three weeks to get him back on the practice field, according to the guidelines of the physically unable to perform list.

But Detroit coach Jim Schwartz cannot say if that will happen at this point, according to Dave Birkett of the Detroit Free Press. The Lions could have promoted Best from PUP to start a three-week window for him to practice beginning on Monday. Instead, general manager Martin Mayhew announced that doctors have not cleared the running back.

I don’t know what the likelihood is,” Schwartz said when asked if there is a chance Best will play this season.

Schwartz said he also did not know if Best will undergo more concussion tests in the next three weeks in order to possibly be cleared for a return to action. He needs to get the green light from an independent neurologist and team physicians.

“I think I said on Monday, I’m on a being-notified basis on that one so I’ll leave it up to other people to comment on that,” Schwartz said.

Best has not played in 53 weeks now.

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Brad Biggs covers the Bears for the Chicago Tribune