NFL training camps are in full swing.
There's never a shortage of desperation, heat or testosterone this time of year, and that leads to plenty of fisticuffs, on and off the field.
Usually, high-profile players manage to stay above the fray.
Newton disregarded his protective red jersey and went after a cornerback during practice. Bryant did his best Floyd Mayweather impersonation after getting tangled up with a defensive back. While both escaped injuries in those skirmishes, Smith will miss 6-10 weeks with a broken jaw after getting punched by a now ex-teammate in the locker room.
The danger with these routine fights is losing a player to an unnecessary injury, which is why it is news when a star is involved.
Bills coach Rex Ryan has two simple pieces of advice for his players - first, don't hit a guy with a helmet on; second, don't hit a guy with his helmet off.
''So in other words, don't fight,'' Ryan said after starting receiver Robert Woods and cornerback Stephon Gilmore came to blows. ''You know, that's what I'd prefer. Sometimes I know it gets heated, every now and then it's just like a little thing and you just let it go.''
The problem is some don't let it go.
It makes it easier to hang onto those grudges with no rules governing fights in training camp. No NFL-imposed fines, no suspensions.
''You go against the same bodies, run the same plays,'' said Panthers Pro Bowl tight end Greg Olsen. ''We know what the defense is going to run, they know what (the offense) is going to run. It's frustrating. It's hot. You've been out there every single day. You get fatigued. Your emotions run hot. It's just normal.''
Most training camp ''fights'' end almost as soon as they begin with teammates stepping into break things up.
Of course, there are exceptions.
Cowboys coach Jason Garrett said skirmishes have always been a part of training camp - and he doesn't necessarily see that changing.
''That's the nature of it, you try to create competitive situations on your team and sometimes you have these guys competing to win and these kinds of things happen,'' Garrett said.
But star players like Newton and Bryant don't have anything to prove.
Competing, though, is part of what makes them who they are.
It wasn't the smartest idea for Newton, who just signed a $103 million contract, to chase down cornerback Josh Norman and tackle him after Norman stiff-armed him during an interception return.
But Newton said he do it over again. He views himself as a football player, not just a franchise quarterback, who is ''all about getting the respect of my guys.''
Many camp fights are the result of trash talk.
Newton did it.
So did Bryant and his sparring partner, cornerback Tyler Patmon. They had been jawing at each other for several plays before exchanging closed-fist blows.
''He wasn't going to back down, I wasn't going to back down,'' Bryant said. ''At the end of the day, we shook hands. We hugged. We respect one another.''
''Guys want to make the team and sometimes tempers flare,'' Avant said. ''But you need it, because no one is going to pay your rent if you get cut from the team.''
An overabundance of testosterone can also be an issue off the field.
That seems to be the situation involving Smith. Jets coach Todd Bowles said what happened was not football related and ''something very childish.''
But Smith isn't the first player to take a cheap shot to the head.
Five years later, Panthers wide receiver Steve Smith punched a helmetless Ken Lucas in the face twice while the cornerback was kneeling on the sideline between plays. Lucas needed surgery to repair a broken nose; Smith was sent home from camp early and suspended by the team for two games without pay.
Still, Olsen said more often than not it's all forgotten by the next day.
''In the inner circles of football locker rooms, on-field fights are really not that big of a deal,'' Olsen said. ''They're inevitable. Once they're broken up, everyone goes their separate ways and it's over.''
Just not when franchise players are involved, or get injured.
AP Sports Writers John Wawrow in Pittsford, New York; Schuyler Dixon in Oxnard, California, Dave Skretta in St. Joseph, Missouri, and Dennis Waszak in Florham Park, New Jersey contributed to this report.
AP NFL website: www.pro32.ap.org and www.twitter.com/AP-NFL