After x-rays, Tony Stewart to begin rehab regimen

After undergoing x-rays of his injured back, Tony Stewart will embark on a rehabilitation regimen designed to hasten his recovery from the burst fracture of the L1 vertebrae he suffered in all-terrain vehicle accident on Jan. 31.

Stewart-Haas Racing announced late Wednesday that doctors are "satisfied with the amount of healing that has taken place" with Stewart's injured back, but added that "future evaluations will be necessary before a timetable is known for Stewart's return to racing."

SHR also reiterated that the three-time Sprint Cup champion is expected to make a full recovery and that plans for an interim driver have not been finalized for the duration of Stewart's time away.

Ty Dillon is driving Stewart's No. 14 car this weekend at Phoenix International Raceway, after stepping in for Stewart two weekends ago at Atlanta Motor Speedway.

Brian Vickers subbed for Stewart during Daytona Speedweeks and last weekend at Las Vegas Motor Speedway.

Stewart, who plans to retire from driving at the end of 2016, has made appearances at the racetrack the past two weekends -- first at Atlanta and again last weekend in Vegas.