ALLEN PARK — Jahvid Best remains the mystery man of Lions training camp.

More than 10 months since his last concussion, the Lions running back has still not been cleared for contact.

The day — actually Aug. 31 — is fast approaching when the Lions have to decide whether to put him on the physically unable to perform list. This would mean no practice and that he would miss the first six games.

“When we get to ... no, no decision has been made right now,’’ coach Jim Schwartz said on Thursday.

Placing Best on the PUP list would give Best and the Lions time.

“Well particularly with concussions, his time is always beneficial. You’ve seen that with a lot of other guys that have come back. That would buy us time if we had to cross that hurdle,’’ Schwartz said.

Best is on a week-to-week basis, not day to day.

Weeks ago he said he no longer suffers any concussion symptoms. He was able to participate in offseason work because it was no-contact.

“He’s doing great. He’s working out hard, he’s just not cleared yet,’’ Schwartz said.

The coach said he wouldn’t compare Best’s concussion problems to those of the Pittsburgh Penguins’ Sidney Crosby because the sports are too different.

“Again, you can’t judge one guy on something else. Everybody’s body is a little bit different, everybody’s reaction is a little bit different,’’ Schwartz said.

Crosby suffered a concussion in early January 2011. He was out 10 months, played eight games and then was sidelined again for three months before he played again.

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