HOMESTEAD, Fla.—Brad Keselowski is leaving his cellphone behind.

Keselowski plans to ditch his phone during NASCAR's Sprint Cup finale Sunday. His decision comes days after NASCAR fined him $25,000 for having the phone in his race car. It was discovered because he tweeted during a red flag at Phoenix International Raceway.

The punishment confused many who wondered why Keselowski was penalized for Sunday's tweets when he was celebrated by NASCAR for doing the same thing during the season opener.

Keselowski felt the same way.

"I'm confused a lot," he said Thursday. "I'll just add that to the list."

Nonetheless, the decision to go without his phone wasn't easy.

"I do feel naked when I don't have my phone," he said. "It's my security blanket. It doesn't matter how I feel about it right now. It is what it is at this point. I just have to move on and focus on the weekend ahead."

Some alleged the Sprint Cup Series points leader was actually being disciplined for his profanity-laced outburst after Sunday's crash-and fight-marred race.

NASCAR dismissed the conspiracy theories, saying drivers had been told after the Daytona 500 that electronic devices—including cellphones—could not be carried inside the race cars going forward.

Keselowski, who takes a 20-point lead over Jimmie Johnson into Sunday's season finale, is looking to win his first Cup title.