The 2015 season once seemed destined to be remembered for tragedy rather than triumph for Kyle Busch. A violent crash during the Xfinity Series opener at Daytona International Speedway in February left him with a compound leg fracture and a broken foot. He missed 11 races. Yet by November, Busch had completed one of the sport’s greatest comeback stories, returning to claim the 2015 Sprint Cup championship. Watching it all unfold was his Joe Gibbs Racing teammate Denny Hamlin, whose own race became memorable for far different reasons after an early gear-oil problem sent his Toyota to the garage for repairs.

“Way to go @KyleBusch,” Hamlin wrote on X after the race. “Way to ‘pound em into the ground’ #champs.” Back then, the two shared the same garage and a close bond built through years of racing together. But as Busch left to join Richard Childress Racing, their relationship evolved. Frenemies might be the word. They’d face each other on the track, trash-talk, and say unflattering things. Yet, it was barely a feud. Call it tough love instead. So, when Hamlin got to know about Busch’s passing on Thursday, he went numb.

“Absolutely cannot comprehend this news. We just need to think of his family during this time. We love you KB,” Hamlin wrote on social media.

The details of his medical condition are still under wraps. It was suspected that his illness was connected to something that happened at Watkins Glen, when he told his team he needed a shot after the race. He had been dealing with a sinus cold.

Then, on Wednesday, he was participating in a simulator session in Concord, North Carolina, which took a frightening turn. He had been Busch had been working inside Chevrolet’s racing simulator when he suddenly became unresponsive, prompting medical attention and transport to a hospital in Charlotte. Hours later, he passed away on Thursday.

The rivalry between Hamlin and Busch was always rooted in the same thing: both believed they should be the best driver in the garage. That constant push fueled years of competition between them. On NASCAR’s all-time Cup Series wins list, Busch sits ninth with 63 victories, while Hamlin follows closely behind in tenth with 61. Before Busch’s passing, the two stood as the winningest full-time drivers in the Cup Series, a reflection of how dominant they were during their years together at Joe Gibbs Racing.

Week after week, they carried the organization, trading wins and leading the team’s hierarchy like a constantly shifting 1A and 1B, with momentum swinging from one to the other depending on the season.

But like Hamlin, Dale Earnhardt Jr. could not process the news either

Few rivalries in NASCAR ever carried the same tension as the one between Dale Earnhardt Jr. and Kyle Busch. Their fan bases rarely saw eye to eye, and the friction between the two drivers only intensified that divide over the years. Much of it traces back to a race to Richmond Raceway in 2008, when Earnhardt and Busch found themselves battling each other for the lead in one of the sport’s most heated moments of that era.

For most of the evening, things stayed under control. But once the race narrowed into a two-man fight for the win in the closing laps, everything changed. With just three laps remaining, Busch made contact and sent Earnhardt spinning, destroying the No. 88’s shot at victory and igniting one of NASCAR’s most bitter rivalries. The reaction from Earnhardt’s fan base was immediate and intense, with Busch later becoming the target of furious backlash that even included death threats.

Time eventually softened the edges of the rivalry. The years that once featured heated battles and resentment later gave way to reflection, with both drivers even sitting down together on podcasts to revisit the moments that defined their relationship on the track. Beneath all the tension and competition, there was also respect. And so, for Earnhardt, the loss is undoubtedly personal because few drivers challenged him, frustrated him, and pushed him harder than Busch did.

“Kyle and I had a really challenging existence for many years,” Earnhardt wrote on X. “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. 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.”

Now, though, he is reflecting on his late friend’s legacy, among others.

NASCAR world mourns Kyle Busch’s passing

“Completely heartbroken to hear the news of Kyle’s passing… He was the bar we all measured ourselves against,” Kyle Larson remarked.

“Kyle Busch wasn’t just one of the fiercest competitors our sport has ever seen; he was one of the most talented race car drivers I’ve ever shared a track with,” Jimmie Johnson wrote.

Johnson and Busch spent quite a few years together at Hendrick Motorsports during the early stages of Busch’s Cup Series career. Busch drove for Hendrick Motorsports from 2003 through 2007 before becoming one of NASCAR’s defining stars over the next two decades.

“This doesn’t even feel real typing this… no race I run from now on will ever feel the same,” Chase Briscoe voiced.

“I’m so sad and stunned to hear the news about KB… Kyle was the best mentor you could ever have,” William Byron said.

“I’m a bit shell-shocked at the moment… We love you, KB. You done good. Rest easy, man,” Pat McAfee said.

“There aren’t really words for today… Rest easy, Rowdy. The sport won’t be the same without you,” Ricky Stenhouse Jr. said.

“Kyle was not just a mentor, but also a friend… I’m heartbroken at the loss of this champion,” Erik Jones remarked.

“In shock, absolutely heartbroken and saddened for the loss of Kyle Busch… KB is one of the best to ever do it,” AJ Allmendinger said.

“I just talked to him Friday… The devastation and sadness is beyond words,” Clint Bowyer said.

“Every day is a privilege, and today is a truly sad reminder of that… you will be deeply missed,” Carson Hocevar said.

“Absolute shock. Very hard to process. Hug your loved ones,” Brad Keselowski wrote.

“I have so many pictures & stories about Kyle… He made me better,” Shannon Spake penned.

“Unfathomable news… His guidance and leadership was something I will cherish forever,” Corey Heim wrote.

“At a loss for words. Thinking and praying for the entire Busch family,” Connor Zilisch said.

“I’m in shock and speechless,” Mark Martin voiced.

One quote keeps hanging over everything now. After winning at Dover last week, Busch was asked how many more races he wanted to win before retirement. His answer sounded casual then. It doesn’t anymore.

“You take whatever you can get, man. You never know when the last one is going to be, so cherish them all — trust me,” he had said.

That ended up being the final win of a career that changed NASCAR. Busch leaves behind wife Samantha, children Brexton and Lennix, and a record 234 wins across NASCAR’s top three national series. More than anything, though, he leaves behind a garage full of drivers who grew up chasing him, racing him, arguing with him, and eventually respecting him.