BRISTOL, Tenn. (AP) — It only took one session in the dirt for Kevin Harvick to change his mind about NASCAR’s latest experiment.

Harvick was one of the loudest detractors headed into the first Cup Series race on a dirt track since 1970. He had been dreading Sunday’s race at Bristol Motor Speedway from the moment NASCAR put this harbinger on the schedule.

And it was only two weeks ago that Harvick groaned about 250-laps around the Tennessee bullring — he called it “the longest dirt race in the history of mankind” — and predicted it would be a struggle for drivers so accustomed to concrete to even make it to the checkered flag.

After 51 laps of practice Friday — in a truck, no less — Harvick had done an about-face.

“This has been a weekend that I had big X’s through, and honestly, that’s as much fun as I’ve had in a race car in a long time,” Harvick said. “Just getting over my anxiety and being able to do something way outside my comfort zone was rewarding.”

Harvick is one of seven Cup regulars entered in Saturday night’s Truck Series race so they could get some experience on dirt. It will be his first Truck Series race since 2015 but Harvick wanted as much track time as possible on the red clay surface.

NASCAR returned to a traditional three-day race weekend for the first time since the pandemic began and scheduled a pair of Friday practice sessions for both the Truck Series and the Cup Series. When practice was complete, truck series regular Ben Rhodes called Harvick a contender.

The favorites for Sunday, though, are expected to be the drivers who both started their careers racing on dirt and still do throughout the NASCAR season. But race favorite Kyle Larson had a huge temperature spike during Friday’s final practice and an engine change will send him to the back of the field at the start of Sunday’s race.

And of the 10 fastest drivers on the day, very few were dirt regulars. Ryan Blaney was fastest overall, followed by Alex Bowman and then Denny Hamlin, who last raced on dirt as an 8-year-old in a go-kart.

Blaney felt the track conditions changed dramatically from the start of the day through the final practice session — and not for the good.

“It’s rough, slick. Really rough, actually,” Blaney said. “The track is kind of coming up and there are crazy big divots. It’s rough.”

Blaney also said dust made for poor visibility until the sun set.

The cars were indeed much slower — at least 5 seconds slower a lap from times turned on Bristol’s concrete — and Hamlin expected some changes to be made to either the track surface or the race format before Sunday.

The starting lineup will be set by heat races on Saturday and pit stops during the race will be controlled with only tire changes permitted. Rain is expected at Bristol both Saturday and Sunday, which would impact a track surface that has drivers concerned about tire wear.

Rain on Thursday had already made for changing track conditions.

“It was like a really thin layer of flaky dirt on top of the black, hard-packed, rubbered down dirt when I walked on it this morning. Then that went off pretty quickly,” said Blaney. “I just wish it was a little bit smoother because there are so many ruts and things like that, but maybe they’ll be able to put their heads together and work on it.”

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