LAS VEGAS (KLAS) — Still bothered by concussion symptoms, Kurt Busch will miss his fourth consecutive NASCAR race Sunday, the Cup Series Federated Auto Parts 400 at Richmond, Virginia.

Busch, 44, a Las Vegas native, was injured in a crash during qualifying at Pocono Raceway on July 23.

Busch, who won the Cup Series championship in 2004, announced Wednesday on his Twitter account that he wouldn’t drive at Richmond, saying “my body is not 100% able to sustain the intense race conditions.” also reported that Busch apparently had not received medical clearance to drive the No. 45 Toyota for his 23XI (pronounced 23-11) team.

Busch thanked supporters in his tweet and wished Ty Gibbs, his replacement in the No. 45 Toyota, the best of luck.

“I am making progress and pushing hard each day,” he said in his tweet. “I am encouraged by my team of doctors, and we will continue to do everything it takes to return to competition.”

Busch, a two-time winner at Richmond, scored his lone Cup Series win this season in May in a dominant performance at Kansas Speedway.

Busch is in his first year with 23XI, which is owned by former NBA star Michael Jordan and Denny Hamlin. In 776 Cup Series starts, Busch has 34 career victories.