Dallas Cowboys wide receiver Dez Bryant was at the centre of a mass brawl in a pre-season training camp with the St. Louis Rams.
The Cowboys were put through their paces in a pair of training drills alongside the Rams until numerous altercations ended proceedings.
The second of two joint practices had to be called to a halt due to a melee with Bryant at the centre. The first day had passed without incident.
Tuesday's practice at the Cowboys' camp facility ended about 30 minutes earlier than expected after the skirmishes on the field where the St. Louis offence and Dallas defence were scrimmaging.
A third fight between the Cowboys and Rams included a punch on Bryant and ended the practice, although it wasn't clear who threw the punch. Dallas cornerback Tyler Patmon, who fought with Bryant earlier in camp, had several red marks on his face.
"Well, we got through a day and three-quarters. We had really good work and then unfortunately things got out of hand and we shut it down,” Rams coach Jeff Fisher told NFL.com.
“It's unfortunate, there's no excuse for it. You can't blame it on anybody, it just happened. One thing lead to another and it happened. Fortunately no one got hurt.
"There's no place for (fighting) in our game. There's no place for that from a standpoint of being role models in this game and representing this game for kids. That's not how this game goes."
As well as team-mate Bryant and Patmon trading blows earlier this summer, the Houston Texans and Washington Redskins marred their pre-season routines with a punch-up of their own this month.