Denny Hamlin misses race at Auto Club, Sam Hornish Jr. fills in

Denny Hamlin will miss Sunday's Sprint Cup Series race at Auto Club Speedway because of a sinus infection that is affecting his vision, according to Joe Gibbs Racing president JD Gibbs.

Gibbs made the announcement approximately 30 minutes before the green flag of Sunday's race. Sam Hornish Jr., driving a limited Nationwide Series schedule for the team this season, will fill in for Hamlin.

Gibbs also said that Hamlin was going to the hospital for further treatment and doctors told Hamlin not to race.

Last year, Hamlin was racing for the lead on the final lap of the race at ACS with Joey Logano and Kyle Busch when he and Logano made contact. Hamlin hit head-on into an inside wall and suffered a fracture to his lower back. He missed four races before returning.

His absence is also the first test of NASCAR's new Chase rules. Officially, a driver must attempt all 26 pre-Chase races to be eligible for the Chase. If Hamlin wins a race or is high enough in points to qualify for the Chase, NASCAR confirmed he would be covered by the medical exemption in the Chase format. The sanctioning body left wiggle room when announcing the new rules for the Chase for a case like Hamlin's.

Since Hamlin is not starting the race, he will not receive points.

Hornish was a last-second sub for AJ Allmendinger at the 2012 Coke Zero 400 when Allmendinger was suspended by NASCAR for failing a drug test. Hornish was in California on standby for fellow JGR driver Matt Kenseth, whose wife Katie is expecting the couple's third child very soon.

UPDATE: JGR announced Sunday evening that Hamlin had been released from a California hospital and would be evaluated in Charlotte, N.C., later in the week. Hornish finished 17th in Sunday's race.

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Nick Bromberg

is the editor of From The Marbles on Yahoo Sports. Have a tip? Email him at nickbromberg@yahoo.com or follow him on Twitter! Follow @NickBromberg