Busch was in his 22nd full-time season in NASCAR’s top division, where he won two Cup Series titles in 2015 and 2019.

Kyle Busch, a two-time Cup Series champion who won more races than anyone across NASCAR’s three national series, has died. He was 41.

The Busch family, Richard Childress Racing and NASCAR issued a joint statement on Thursday saying Busch died after being hospitalised. No cause of death was given.

Busch’s family said earlier on Thursday that he was hospitalised with a “severe illness,” three days before he was to compete in the Coca-Cola 600 at Charlotte Motor Speedway.

Busch was testing in the Chevrolet racing simulator in Concord on Wednesday when he became unresponsive and was transported to a hospital in Charlotte, several people familiar with the situation told The Associated Press on condition of anonymity because details have not been disclosed by Busch’s team or family.

Busch was the younger brother of Kurt Busch, a NASCAR Hall of Famer. He’s survived by wife Samantha and children Brexton and Lennix.

“Our entire NASCAR family is heartbroken by the loss of Kyle Busch,” the statement said.

“A future Hall of Famer, Kyle was a rare talent, one who comes along once in a generation. He was fierce, he was passionate, he was immensely skilled and he cared deeply about the sport and fans.”

The statement went on to say that “throughout a career that spanned more than two decades, Kyle set records in national series wins, won championships at NASCAR’s highest level and fostered the next generation of drivers as an owner in the Truck Series. His sharp wit and competitive spirit sparked a deep emotional connection with race fans of every age, creating the proud and loyal ‘Rowdy Nation.'”

The news comes 11 days after Busch radioed into his crew near the end of a Cup Series race at Watkins Glen, asking a doctor to give him a “shot” when he finished the race. According to the TV broadcast, Busch had been struggling with a sinus cold exacerbated by the intense G-forces and elevation changes at the New York road course.

Busch finished the race in eighth place.

Busch competed at Dover last weekend and won the Trucks Series race for Spire Motorsports. He then finished 17th at the NASCAR All-Star race, his final race.

“Absolutely cannot comprehend this news,” NASCAR driver and former teammate Denny Hamlin posted on social media. “We just need to think of his family during this time. We love you KB.”

Added driver Brad Keselowski on social media: “Absolute shock. Very hard to process.”

A polarising figure known as “Rowdy” and “Wild Thing” for his post-race fights, regular feuds with other drivers and sometimes outlandish behaviour, the multi-talented Busch stormed on the Cup Series scene in 2005 by winning Rookie of the Year.

He went on to win championships in 2015 and 2019 for Joe Gibbs Racing.

“His impact on our organisation and on the sport of NASCAR will never be forgotten,” the team said in a statement.

From Las Vegas, Busch experienced unrivalled success across NASCAR’s three national series, winning a combined 234 Cup, O’Reilly Auto Parts and Trucks Series races. He had 63 Cup victories along with 102 O’Reilly Auto Parts wins and 69 Trucks victories – both records.

Busch was fired early in his career by Hendrick Motorsports to make room on the team for Dale Earnhardt Jr.

“Kyle and I had a really challenging existence for many years,” Earnhardt said in a statement. “But we luckily took the time to figure out our differences and that was something he instigated with a conversation in his bus around how we each managed our racing teams. I was super eager for us to get on better terms. But it was he who made the effort for that to be possible.”

Busch moved on to Joe Gibbs Racing, where he experienced the vast majority of his career success. But Busch was let go when there was no sponsor after the 2022 season and joined Richard Childress Racing, where had struggled to win races.

His lack of success led to a recent spat with former JGR teammate Hamlin, who appeared to criticise Busch on the “Actions Detrimental” podcast. Hamlin said, “If you’re expecting Kyle Busch to just go back to victory lane on a regular basis, you are kidding yourselves.”

While Hamlin later said he meant no harm by the comments and was just making an observation, Busch took exception and said he could make Hamlin’s life “hell” on the racetrack.

While several laps down at last month’s race at Kansas, Busch raced Hamlin hard instead of allowing the race leader to pass. That decision held up Hamlin during a crucial stage of the race and Tyler Reddick won the race after Hamlin faded late.

After winning the trucks race at Dover last week and showing an uptick in speed, Busch seemed to make a veiled jab at Hamlin, saying, “I guess I just remembered how to drive.”