Denny Hamlin’s driving status for the Talladega Superspeedway weekend remained uncertain Thursday.

Hamlin tweeted early in the week that he is ready to race, but there was no indication Thursday that NASCAR’s medical personnel had given him clearance.

NASCAR had not made any announcement in regard to approving Hamlin’s Talladega driving plans late Thursday. Practice for Sunday’s Aaron’s 499 is scheduled to begin Friday.

Hamlin fractured his lower back in a crash at Auto Club Speedway in California in March. He has missed four races.

Brian Vickers and Mark Martin have filled in for Hamlin in the Joe Gibbs Racing No. 11 Toyota. Vickers is scheduled to replace him again Sunday if he is not approved to race.

If Hamlin starts the race, he probably would drive only a portion of the event and Vickers would replace him for the balance.

Mike Hembree is NASCAR Editor for SPEED.com and has been covering motorsports for 31 years. He is a six-time winner of the National Motorsports Press Association Writer of the Year Award.