Five-time Sprint Cup champion Jimmie Johnson is known as one of the calmer, most level-headed people on NASCAR's pit road, but you wouldn't know it after the furious exchange he initiated with Kurt Busch after Sunday's rain-interrupted Good Sam RV Insurance 500 at Pocono Raceway during which he called Busch a "smartass" and a "crybaby".

It began when Jimmie Johnson made a dive for the lead at the final restart and went three-wide with Brad Keselowski and Kyle Busch; he lost out in that one and the duo pulled away, leaving him to contend with Kurt Busch for third place instead over the concluding 15 laps of the unique 2.5-mile "tri-oval" circuit. The fighting got fiercer as the chequered flag approached, and on the final lap the two exchanged side-swipes several times - which Johnson didn't appreciate.

Once back in the pits, he stormed over to the Penske area to have words, even before Busch had managed to get out of his car.

"He's pretty much a smartass and wants to run his mouth so I had to go over there and say something," Johnson fumed. "He's a big crybaby and wants to take shots at me when he can ... He's good for running his mouth. He can keep running it. I'll shut it for him."

Busch seemed startled by Johnson's fury. "I should just pull over?" Busch yelled in response when Johnson started in on him. "I raced you clean ... It's okay to race every now and then."

Busch didn't believe either of them had done anything wrong and said that "It was as clean as I've ever seen it. Why can't we race like this and put on a show for the fans and not have a problem with it?"

Johnson's gripe stemmed from his view that after having given Busch a lot of space and room during those final laps, Busch had paid him back by cutting him off and swiping him in order to take third place in the final seconds.

"I took a lot of patience and gave him a lot of courtesy throughout the course of the day running him down," Johnson said. "I could have run into him ... I had a few chances to play dirty and I didn't.

"It took me that entire fuel run to set up that pass on him, and I finally got it done and then that problem happens," he said. "I just don't understand why, when I finally get position on him, he's got to run all over the side of me down the straightaway ... Then, off of 2, he claims I turned down on him. And I don't have a clue. He ran over me on the corner exit, and that's where it all started."

Busch's view was different: "He came off the turn and did a jab to me left; I did a jab back to the right," he said. "If we watch the tape, we'll see that the #48 swerved into us first and I know that before even watching the tape.

"If a five-time champion doesn't know how to race, forgive me," he said after the pit road row, which appears to have reopened wounds from last year when the two had multiple clashes throughout the season - including the #48 wrecking the #22 at Pocono. "I raced him hard. I raced him smart. I raced him clean. And he wants to come over here and bitch about it."

Busch's temper was still fiery when he faced the press afterwards - and found the questions dominated not about the racing but about the post-race clash with Johnson. "You wonder why we don't [race hard]?" he responded to one journalist's enquiry. "Because we have to come in here and answer ... questions like this."

Earlier, Busch's parting shot as Johnson walked away was to yell, "You can't stand losing, can you?" - and Johnson said this was at least one thing that they could agree on.

"No I can't," Johnson responded. "I hate losing ... But that wasn't the deal today. That wasn't it."