Red Bull Racing Team officials announced Thursday that due to a recent diagnosis of a medical condition, Brian Vickers will not compete in this weekend's NASCAR racing activities at Dover International Speedway and will be replaced by Casey Mears (left).

The regular driver of the No. 83 Red Bull Toyota was hospitalized Wednesday evening and continues to undergo testing and further evaluation, the team says, although it would not disclose the nature of Vickers' ailment.

"It is unfortunate that I will not be able to participate in the Dover race. Casey is a good friend of mine, and I know he will do his best for the No. 83 team this weekend," said Vickers in a statement released by the team.

"Our main concern right now is with Brian and his health and recovery", said Jay Frye, RBRT general manager and vice president. "All things are looking good at the moment; this is just a minor setback. We appreciate Casey filling in this weekend and know he will represent the team well."

Mears has been without a regular Sprint Cup ride for 2010 after being released by Richard Childress Racing, although he has made a couple of one-off starts and was on standby at Joe Gibbs Racing to fill in if necessary for Denny Hamlin following the latter's knee surgery.

Johnny Sauter is expected to return behind the wheel of the No. 36 car of Tommy Baldwin Racing, which he raced at Talladega, as Mears was initially entered to drive that car this weekend.