DAYTONA BEACH, Fla. – NASCAR placed Kyle Busch and Carl Edwards on probation Wednesday for the next six Sprint Cup Series races, the result of their on-track incident last weekend at the end of the race at Bristol Motor Speedway.

During the cooldown lap after Edwards' Ford took the checkered flag for Roush Fenway Racing, Busch drove alongside Edwards and bumped his car. Edwards responded by driving the nose of his car into the right side of Busch's Toyota, spinning him out.

The postrace incident was apparently a reaction to Edwards nudging Busch aside with 30 laps to go Saturday night. Busch had led the previous 415 laps.

Busch was unrepentant after the race, saying, “We'll go on and we'll race him that way in the Chase if that's the way he wants to race.”

Edwards wasn't backing down, either.

“A real smart racer explained it to me this way after he wrecked me and I was real mad. He said, 'I just had to look at your rear bumper and decide if you would do this to me, and you had, and so it was a real simple decision,'” Edwards said. “I'd do it again.”

Both drivers were later summoned by NASCAR to explain their actions.

This is just the latest development in a growing rivalry between the 23-year-old Busch and the 29-year-old Edwards, the winningest drivers in Cup this season.

Busch, who drives for Joe Gibbs Racing, has been the most dominant driver this season, winning eight times and building a lead of 212 points over runner-up Edwards in the Cup standings with two races remaining before the start of the 10-race Chase. But Edwards, who now has six wins, has come on strong in recent weeks, winning two in a row and three of the last four races.

The points race would have been even closer if not for a penalty Edwards received for racing without a cover on his oil tank after winning at Las Vegas. He was docked 100 points and NASCAR also took away the 10 bonus points for the win that would have transferred to the Chase.

Once the 12-man lineup for the Chase is set, their point totals will be reset to 5,000 and they will then be seeded by victories. If the Chase began this week, Busch would be on top with a 30-point lead over Edwards.