CONCORD, N.C. -- Hendrick Motorsports announced Tuesday that Dale Earnhardt, Jr. has not yet been cleared by doctors to return to at least the next two NASCAR Sprint Cup Series events due to a concussion. 

Four-time Cup series champion Jeff Gordon will continue his role as substitute driver for the No. 88 team at Watkins Glen International on August 7 and Bristol Motor Speedway on August 20. 

According to Earnhardt's weekly podcast, the two-time Daytona 500 champion is still experiencing issues with his balance and a condition known as gaze stabilization. The team said Tuesday that Earnhardt underwent further evaluation at the University of Pittsburgh Medical Center Sports Medicine Concussioin Program. 

Earnhardt said during Monday's Dale Jr. Download show that doctors believe his injury occured during a crash at Michigan International Speedway on June 12. Earnhardt competed in three races following the Michigan race before sitting out the New Hampshire 301 on July 17.

"I've never had a concussion that came on weeks after the event," Earnhardt said. "Most of them you feel it immediately, and then they get better over time, whether it's 72 hours or a month. This has been the opposite.

"This is scary for me because of the way it's been different. I'm having balance issues. I've never had balance issues before. The eye issues with the stability, I've never had that before."

Team officials hope that the week off between Watkins Glen and Bristol will help Earnhardt, but aren't in any rush to see him behind the wheel. 

"We have a break in the schedule after Watkins Glen, so the extra week of recovery time will certainly be a benefit," said team owner Rick Hendrick. "Dale will be back when he's ready, and we're looking forward to that happening, but the priority continues to be his health and well-being. We'll keep our focus on that and let the doctors guide us."

Sunday's race at Watkins Glen will be Gordon's 800th career start in Cup series competition. He is NASCAR's all-time leader in road course wins with nine, including four at Watkins Glen. He also has five victories at Bristol, with the last occuring in 2002.