Dallas Cowboys wide receiver Dez Bryant was punched in a fight between the Cowboys and the St Louis Rams in practice yesterday.
The teams have been doing a series of joint-practice sessions ahead of the new season, but Tuesday was littered with several fights throughout the day.
In the final fight of the day Bryant was on the wrong end of a punch, although it is not known who threw it.
Cowboys executive vice-president Stephen Jones told reporters: "I hate it. At the end of the day we know why it happens. I can't imagine that we can't continue to have joint practices and get this right just like we do a lot of things. But we're going to have to continue to emphasise that stuff is not what we want."
This is the second time this month that a joint-practice session has been cancelled due to fighting, following the Houston Texans and Washington Redskins two weeks ago.
