Kyle Busch is expected to miss this weekend’s Coca-Cola 600 at Charlotte Motor Speedway after his social media accounts said the 41-year-old driver has been hospitalized with a severe illness and is undergoing treatment. He will not take part in any of his scheduled activities at the track in Concord, N.C., this weekend.

Richard Childress Racing said Austin Hill will drive Busch’s No. 8 Chevrolet in his place. Hill, who drives the No. 21 for RCR in the O’Reilly Auto Parts Series, steps in for one of NASCAR’s most recognizable names while the team waits for Busch to recover.

Busch’s social accounts said, “Kyle has experienced a severe illness resulting in hospitalization.” They added that he is “currently undergoing treatment” and would not compete in any of his scheduled activities this weekend at Charlotte Motor Speedway. In a separate statement, Richard Childress Racing said Busch’s health is its “utmost priority” and that he and his family have the full resources of RCR behind them.

The team also said Busch’s No. 8 Chevrolet will be “ready and waiting for him” and thanked Hill for stepping in. It asked fans to keep Busch and his family in their prayers and to respect their privacy during what is now a sudden interruption to a major race weekend.

Busch is a two-time NASCAR Cup Series champion, and his absence removes a proven contender from one of the sport’s biggest races. For now, the focus at Charlotte has shifted from competition to health, with RCR making clear that the car will stay prepared and the seat will stay open until Busch is well enough to return.