Kurt Busch will be unavailable to race the FireKeepers Casino 400 at Michigan International Speedway Sunday because he's still recovering from a concussion.

Busch was injured after crashing in qualifying July 23 at Pocono Raceway. 

He has missed the last two races with concussion-like symptoms.

Ty Gibbs will again replace Busch in the No. 45 Toyota for 23XI Racing.

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Ty Gibbs replaces Kurt Busch

Ty Gibbs, driving for an injured Kurt Busch, prior to the NASCAR Cup Series M and Ms Fan Appreciation 400 July 24, 2022, at Pocono Raceway in Long Pond, Pa. (Rich Graessle/Icon Sportswire via Getty Images)

"I am continuing to make improvements every day," Busch wrote in a tweet Wednesday. "I know Ty will continue to do a great job representing 23XI and the No. 45 Monster Energy team this weekend in Michigan. I am working hard to get back to 100%, and it’s my hope to be back in the car at Richmond Raceway. Thanks to everyone for the continued support and I look forward to being back on track soon."

Busch appeared at the Charlotte FC match Wednesday. He said doctors told him to seek stimulation, and he was seen banging a drum at Bank of America Stadium.

Kurt Busch at Pocono

Kurt Busch's No. 45 car spins during qualifying for the NASCAR Cup Series at Pocono Raceway July 23, 2022, in Long Pond, Pa. (AP Photo/Matt Slocum)

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"We're looking forward to Kurt being back to 100% and on track," 23XI racing said in a statement.

Gibbs finished 17th at Pocono and Indianapolis. Michigan will be his first traditional oval in a NASCAR Cup Series race.

Kurt Busch at Nashville

Kurt Busch, driver of the No. 45 Monster Energy Toyota, waves to fans onstage during driver introductions prior to the NASCAR Cup Series Ally 400 at Nashville Superspeedway June 26, 2022, in Lebanon, Tenn. (Logan Riely/Getty Images)

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Busch has a waiver to hold his spot in NASCAR’s playoff field should he qualify. He does have a spot based on his May victory in Kansas.

The Associated Press contributed to this report.