Johnson and Finnegan got physical on the previous play, with Johnson shoving Finnegan in the back. Finnegan walked away from that one.
Finnegan then set off the brawl on the next play by jabbing at Johnson's neck and face mask at the line of scrimmage. Johnson ripped off Finnegan's helmet and landed at least two punches to Finnegan's head and neck. The two spun each other, and Finnegan tore off Johnson's helmet before players and referees intervened.
This was Round 2 between Johnson and Finnegan. Last season, Johnson was fined $7,500 for taking Finnegan to the ground by the face mask during a scuffle after a play in a 34-31 Texans win.
"I wish that I could take back what happened, but I can't," Johnson said Sunday. "I'm pretty sure I'll be disciplined for it."
The Associated Press contributed to this report.