A late caution at Atlanta Motor Speedway gave Kevin Harvick one futile, final chance to beat Jimmie Johnson.

The showdown went to Johnson and Hendrick Motorsports in the first of what could be a long season of battles between NASCAR's powerhouse team and Stewart-Haas Racing as the allies begin the yearlong dissolution of their partnership.

SHR stunned the industry 72 hours after the season-opening Daytona 500 by announcing it will leave Chevrolet and its alliance with Rick Hendrick at the end of this year. Tony Stewart and Gene Haas are defecting to Ford in a coup that very few saw coming. Even Hendrick admitted Sunday to reporters that SHR's move "kind of caught me by surprise."

SHR's move to Ford is surprising on several fronts:

— Stewart is a General Motors guy, and has been for all but one of his 18 seasons as a NASCAR driver. He drove Toyotas for one season at Joe Gibbs Racing, his last before he bolted for a co-owner position at SHR.

— Harvick, one of the four drivers in the SHR stable, has never driven anything but Chevrolets in his Cup career. He and Stewart both won Cup titles for Chevrolet at SHR.

— Haas leaned on Rick Hendrick when he entered NASCAR, and it was Hendrick who helped broker the deal that brought Stewart into the race team.

— As customers of Hendrick Motorsports, SHR bought chassis and engines from NASCAR's top team. A technical alliance was formed, and by the time Harvick won the 2014 title, the data sharing was flowing back and forth between the two organizations.

Alas, that's where the problems may very well have started.

Few would deny that SHR has outperformed Hendrick the last two seasons, which couldn't possibly sit well with the folks at Hendrick. How could Harvick and Kurt Busch be driving Hendrick equipment and beating Hendrick drivers each week?

And somewhere along the line the relationship between Johnson and Harvick that dates to their early racing careers in California became strained. It was Johnson who was in and out of Harvick's trailer during the 2014 season finale, where the six-time champion was an open book and gave Harvick any advice possible to aid Harvick's bid to win his first Cup title.

Fast-forward to last September when the two made contact in the opening race of the Chase for the Sprint Cup championship at Chicago. Johnson immediately went to Harvick's motorhome after the race to defuse the situation, and Harvick exited his bus practically swinging. He had no time to hear Johnson out and no desire to smooth out the relationship.

Asked a few weeks later just what had soured between the two, Harvick smugly offered only, "Oh, there's not enough time to get into that."

It seemed puzzling last fall, but in light of the move to Ford, now may be an indicator to a fractured relationship between two of the top Chevrolet teams in NASCAR.

In announcing next year's move to Ford, Stewart explained that the manufacturer change gives SHR a chance to step out of the Hendrick shadows and become more self-sufficient. The team will get its engines next year from Doug Yates instead of Hendrick, and will slowly this season begin to build its own chassis and wean itself off of Hendrick support.

But Stewart also indicated, with little elaboration, that something had shifted in a partnership that began when Haas put his first Cup car on the track in 2002.

"I feel like our relationship with Hendrick has been changing a little bit over the last year," Stewart said during last week's Ford announcement. "The technical side of it has changed quite a bit going into this season, so we've kind of been working this direction."

Translation: Our people are just as smart as Hendrick's and we don't necessarily need or want to be sharing all our secrets with them anymore.

But this eventual divorce has the potential to be bumpy over the next 35 races.

At some point, the information flow between the two teams will trickle down to next to nothing, just as Chevy may need to stop being so open with SHR as the season progresses. Those shifts could come when SHR is battling Hendrick drivers in the 10-race playoffs for the title.

And, very few are convinced that Harvick is totally on board with this move. He played the role of content company man when he addressed SHR's eventual move, but he never uttered the word "Ford." He has a personal services contract with Chevrolet, and the manufacturer has leaned on Danica Patrick and Busch for marketing support over the years.

Although Stewart dismissed any idea of turmoil between the two organizations as the season goes on, this has the potential to be very, very sticky as the two organizations battle each other for wins and spots in the championship field.

"Our partnership with Ford doesn't start until next year and we're excited about it, but this year we're still a Chevy team and we're still committed to going out and doing everything we can to win races and a championship for them," Stewart said. "That's what we do."