Tributes are flowing after the popular racer was hospitalised and died days before one of the biggest races of the year.

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

The Busch Family, Richard Childress Racing and NASCAR issued a joint statement Thursday saying that Busch died after being hospitalised.

No cause of death was given.

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

“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.

“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.’”

Busch is survived by wife Samantha, son Brexton, who celebrated his 11th birthday this week and is already making his way up the motorsport ranks, and daughter Lennix, 4.

Busch’s older brother Kurt is also a Cup Series champion and a NASCAR Hall of Famer.

Kyle Busch recorded two wins in the third-tier Truck Series this year — saluting at Dover just six days before his death.

He said he would always celebrate wins at any level “because you never know when the last one is”.

That victory came a week after there was concern for his health during a race at Watkins Glen, asking his team over the radio to meet with a doctor and receive “a shot” after the chequered flag.

According to the TV broadcast, Busch had been struggling with a sinus cold that was exacerbated by the intense G-forces and elevation changes at the New York road course.

Busch started on pole for the top-tier Daytona 500 this season but had struggled for results in the Cup Series, recording two top-10 results from the first 12 races of the year.

Alongside his two Cup Series titles, Busch also holds the record for the most race wins (234) across NASCAR’s three tiers — 63 Cup victories with 102 in the second-tier and 69 Truck wins.

Former teammate Denny Hamlin wrote: “Absolutely cannot comprehend this news. We just need to think of his family during this time. We love you KB.”

Brad Keselowski said: “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.

Dale Earnhardt Jr acknowledged his “really challenging existence” with Busch as he paid tribute and revealed the pair’s plans for the near future.

“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,” Earnhardt Jr said.

“I was super eager for us to get on better terms. But it was he who made the effort for that to be possible. We did some media together also to laugh through some of the things we put each other through many years ago.

“Most recently we had even been discussing him running my Late Model at Wilkesboro this summer. He seemed extremely happy and we had planned to meet up next Thursday to get his seat to the shop. He laughed over the idea of his fans and JRM fans having to cheer in unison during that race.

“Kyle was one of the greatest drivers in NASCAR history. No one can deny that. But he was also a father, a husband, brother, son, and a friend to many.

“My heart is broken for the Busch family. I will never be able to make sense of this loss but I am thankful that we had found a way to become friends.”

Race-winning rising star Carson Hocevar shared a photo of his younger self meeting Busch.

“Every day is a privilege and today is a truly sad reminder of that,” he wrote.

“This little boy in this picture hated you on Sundays. But he loved to hate you, and you made it very difficult to hate and not become a fan when your passion for racing showed, when you would show up to his home town to race at his home tracks. He will be forever grateful for that.

“From a fan, to a hater, to a competitor, to a teammate, and to even maybe a friend. I share that story because this little kid in the picture was not anywhere near the true number that you impacted for the better just through racing.

“You will be deeply missed. both on the race track, but certainly off.”

Busch was viewed as a racing prodigy.

He was said to be ready to race at NASCAR’s top level at 16, but a cigarette settlement banned his debut and he had to wait until he was a 18. At the time Kurt Busch said “if you think I’m good, wait until you see my brother”.

Kyle Busch’s unexpected death is just the latest tragedy to hit NASCAR.

Last December, former driver Greg Biffle, his wife and two children and three others died in a plane crash in Statesville, North Carolina.

One week later Hamlin lost his father in a house fire.

— with 7NEWS: https://7news.com.au/sport/motorsport/beloved-nascar-champion-kyle-busch-dies-suddenly-aged-41-c-22320914