ENGLEWOOD, Colo. (AP) Although both teams hailed it as a productive day, the Dallas Cowboys' joint practice with the Denver Broncos on Thursday at times resembled an undercard at the octagon instead of a prelude to Saturday night's preseason opener.

"Tempers flared a little bit but that's just the nature of football," Broncos linebacker Bradley Chubb said. "Everybody's out there competing and trying to get each other better."

The teams used both fields at UC Health Center, and the one with the Cowboys' offense and Broncos' defense featured more than a half-dozen skirmishes, including Denver defensive end Marquiss Spencer throwing a series of roundhouse punches at Dallas center Marc Farnick.