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NASCAR revealed on Tuesday that it will not penalize Tony Stewart or Joey Logano for their post-race altercation last Sunday at Auto Club Speedway.

The sanctioning body posted on its Twitter account that "NASCAR will issue no penalties from last weekend's events at @ACSupdates."

Following the conclusion of the Auto Club 400, Stewart got into a physical altercation with Logano on pit road. Stewart was furious with Logano for blocking him multiple times during a restart with 11 laps to go.

Stewart pushed Logano around, while Logano threw a water bottle at him before crew members from both teams intervened. Stewart later said he's "going to bust (Logano's rear)."

Logano said he would contact Stewart in hopes of resolving the matter. When Stewart was asked if he'll accept Logano's call, he replied, "Hell no. If he wants to talk about it, we'll talk about it. After he threw the water bottle at me like a little girl, we'll go at it now."

During a teleconference, NASCAR Sprint Cup Series director John Darby explained why penalties were not handed down to either Stewart or Logano.

"A few years ago, we backed away from micromanaging drivers' emotions," Darby said. "You would hope in today's world that if somebody didn't win a race, they would be upset about it for whatever reason. That's what our drivers do is they try to win races."

"And keep in mind, there's the checks and the balances, but a couple of drivers at the end of the race arguing a little bit doesn't create a foul in our world today. The crews did a great job of managing their drivers to make sure that it didn't cross the line to where there was physical violence or anything like that. And that's what you would hope."

Logano's skirmish with Stewart came after he and Denny Hamlin made contact with each other and spun while battling for the lead during the final lap. Logano scraped the outside wall in turn 4 but went on to finish third. Hamlin skidded down the track and then slammed hard into the inside retaining wall. His car came up off of the ground and spun around after it ricocheted off of the wall.

Hamlin climbed out of his car under his own power but then laid down on the track, as safety personnel quickly tended to him. Shortly after, he was airlifted to nearby Loma Linda University Medical Center. Hamlin remained hospitalized until late Monday after being diagnosed with a compression fracture in his lower back.

According to a report from USA Today, Hamlin wore a thick back brace when he left the hospital. He also had difficulty breathing. Hamlin said that he had a hard time breathing after the accident occurred.

"The position I was in, I couldn't breathe at all," Hamlin told USA Today. "I'm still having a hard time breathing. Literally, when I felt a pop, I couldn't move at all and I knew I had to get flat to my back to be able to breathe again. That's why I rushed out and just laid flat on the ground to start breathing again."

Hamlin will be evaluated by Dr. Jerry Petty of the Carolina Neurosurgery and Spine Associates in North Carolina later this week. Petty has evaluated numerous NASCAR drivers in the past.

The Sprint Cup Series is off this coming weekend for Easter before heading to Martinsville Speedway, a half-mile racetrack, the first weekend in April. Hamlin's status for Martinsville is unknown at this time. His injury might require surgery.

Hamlin must be medically cleared in order to return to competition.

"I don't believe (medical experts) are going to sign off on Denny competing if they don't believe that he can," Darby said. "And then from there, a lot of it is Denny himself and saying, yeah, look, I'm okay. Him being out there racing, and not being competitive isn't good for him or the team or anybody else.

"So I think there's enough responsibility amongst the drivers, and I think there's enough professionalism that, if they can't do it, they will say they can't do it and put a replacement driver in the car. But all that is yet to be seen with the majority of the decisions being made by the medical folks first."

Hamlin and Logano's incident at Fontana was the latest episode in their on- going rivalry. Last week at Bristol Motor Speedway, Hamlin hit the back of Logano and spun him out in the late going. After the race, the two had heated words with each other followed by a shoving match between both of their teams. Hamlin and Logano then traded jabs on Twitter. NASCAR did not issue any penalties for that altercation.

Not knowing that Hamlin was injured during the last-lap crash at Fontana, Logano said after the race, "(Hamlin) probably shouldn't have done what he did last week (at Bristol), so that's what he gets."

Both drivers have yet to speak to each other since the accident at Fontana.