Dale Earnhardt Jr. will resume his driving duties in the No. 88 Hendrick Motorsports Chevrolet this weekend at Martinsville Speedway after receiving medical clearance on Tuesday.

Earnhardt Jr., who is NASCAR's most popular driver and one of the 12 competitors in this year's Chase for the Sprint Cup championship, was forced to miss the last two races -- Charlotte and Kansas -- after being diagnosed with a concussion days after he was involved in a 25-car accident on the final lap of the Oct. 7 event at Talladega. He also sustained a concussion during a crash while participating in the Aug. 29 Goodyear tire test at Kansas, which had recently been repaved.

Since his diagnosis, Earnhardt Jr. has been evaluated by Dr. Jerry Petty, a neurosurgeon, in Charlotte. Throughout the process, Petty consulted with Dr. Micky Collins, director of the University of Pittsburgh Medical Center Sports Medicine Concussion Program. Earnhardt Jr. was evaluated by Collins on Oct. 16 in Pittsburgh.

On Monday, Earnhardt ran 123 laps in a Sprint Cup Series car during a test session monitored by Petty at the half-mile Gresham Motorsports Park in Jefferson, Ga. Petty then cleared him the following morning after a final neuropsychological evaluation.

"Dale Jr. has done everything asked of him," Petty said in a statement. "He hasn't had a headache since Oct. 12, and we have not been able to provoke any symptoms since that time. I have informed NASCAR and Hendrick Motorsports that he is medically cleared for all NASCAR-related activity."

Prior to the start of Sunday's 400-mile race at Kansas, team owner Rick Hendrick told reporters that Earnhardt Jr. would return to the No. 88 car for Martinsville. Hendrick, though, later rescinded his pre-race comments that Earnhardt Jr. had been cleared, noting that he would not receive authorization until after the test at Gresham.

Regan Smith has substituted for Earnhardt Jr., finishing 38th at Charlotte due to engine failure and then seventh at Kansas. As a result of missing the last two races, Earnhardt Jr. is last in the Chase rankings, 122 points behind leader Brad Keselowski.