NASCAR recently made it clear to drivers that it wouldn't tolerate any Twitter or social media use in its racecars after the motorsport fined Brad Keselowski $25,000 because he used a smartphone in his car Sunday at the Phoenix International Raceway.

Keselowski is currently leading in the Sprint Cup Series standings, but his in-car television showed the 28-year-old using his phone and sending tweets during a 15-minute break when the cars were stopped so crews could clean the track of a wreck that involved Jeff Gordon and Clint Bowyer.

There was controversy surrounding the decision to fine Keselowski, as the driver was not fined in February when he was tweeting during a similar red-flag period at the Daytona 500.

"NASCAR communicated verbally to the drivers/teams that the language in the rule book was clear - drivers could not carry on board their cars electronic devices such as cellphones while they were on the race track," NASCAR spokesman Kerry Tharp said in an email to the Los Angeles Times.

The Penske Racing driver has more than 321,000 followers on Twitter and was also on probation through the end of the season.

"There's no doubt that a unique set of circumstances combined with a championship battle on the line resulted in raw emotions coming into play," said NASCAR vice president for competition Robin Pemberton. "We consider the penalties appropriate and those involved understand our decision and we expect them to abide by them."

Jeff Gordon was also recently fined $100,000 for intentionally wrecking Clint Bowyer at the race that Keselowski was caught tweeting at. Gordon was also placed on probation through December 31, but will be allowed to close out the Sprint Cup Series Sunday at Homestead-Miami Speedway in Florida.

Gordon released a statement saying he takes complete responsibility for his actions on the racetrack and he accepts NASCAR's decision to place him on probation. He added that he looks forward to ending the season on a high note at Homestead.

Jimmie Johnson and Kasey Kahne are currently in second and third place in the Sprint Cup Series, looking to improve on their performance and make a jump to a higher position.