Indianapolis Colts coach Chuck Pagano expects the NFL to discipline Erik Walden after the linebacker ripped off the helmet of Tennessee Titans tight end Delanie Walker and head-butted him during the second quarter of Thursday's game.

League sources told ESPN's Chris Mortensen that Walden is expected to receive a hefty fine but that he's not likely to be suspended.

Walden was penalized for unsportsmanlike conduct for the second-quarter incident but was not ejected from the game. He does not have a history of similar egregious actions, which will likely spare him a suspension for the Colts' next game against Arizona, sources said.

"You have to keep your cool," Pagano said Friday. "We talked about it as soon as he got off the field. I talked to all those guys. No matter how frustrated you are, no matter how the game is going, no matter what the guy did to you, you cannot retaliate. You have to keep your composure. You have to keep your poise no matter what.

"He knows that. Erik is a grown man. He's accountable, and he understands that. He doesn't want to do anything to hurt this team."

Walden answered every question asked after the game and apologized for his actions, saying he was "selfish" for head-butting Walker.

Sources said Walden would have been fined for the manner in which he ripped off Walker's helmet, but his head-butt to the tight end's chin will result in a significant fine.

The Colts were called for three straight unsportsmanlike conduct penalties on that drive by the Titans. Pagano and defensive lineman Cory Redding both said it's the second guy who usually has to pay the price for his actions.

"When those guys play, that's a tough, rugged sport," Pagano said. "They're banging down after down after down. There's stuff happening out there."