An already improving Colts defense is adding linebacker Robert Mathis back into the mix.

The four-time Pro Bowl player expects to play Sunday against Miami after missing the previous three games with a knee injury.

"That's the plan," he said Thursday. "Looking forward to being out there with the fellas again."

Mathis has five sacks in four games this season. He got a limited number of snaps in practice Wednesday, but doesn't expect any limitations Sunday.

"I'm feeling pretty good," he said. "I'm itching to be out there."

Among the people most excited about Mathis' return: defensive coordinator Greg Manusky.

"He's a Pro Bowler," Manusky said. "He's a difference maker, and that's what we're looking for on Sunday out of him."

Mathis' injury has meant more than a loss of production.

"I think more than the play itself, the sacks, is the passion he brings to the game," Colts interim coach Bruce Arians said. "Not to say the guys aren't giving everything they have, but he's got a special fervor, a special passion. He gave a great speech before the last home game and I thought it was great the way he did it, the way he presented it, he challenged each guy. That heartbeat you can't replace."

Mathis is one of several Colts who have dealt with injuries this season. Defensive end Cory Redding and outside linebacker Dwight Freeney have both returned from injuries. So has inside linebacker Pat Angerer.

The Colts aren't in the clear yet - cornerback Vontae Davis has been ruled out with a left knee injury.

"He's had a couple of injuries that he's not normally had in the past," Arians said. "An unfortunate knee injury he got in this last ballgame because we'll miss him. He's been a very valuable player for us."

Even with the adjustments the coaching staff has been forced to make, the defense has allowed just 26 points combined in wins over Cleveland and Tennessee the past two weeks. Mathis likes what he has seen from his teammates, but it has been difficult for the 10-year veteran to be a 6-foot-2, 245-pound cheerleader.

"I never like to be a guy that just sits back and watches," he said. "I always like to be in the fire."

It will be just the third time this season that Mathis and fellow longtime pass rusher Freeney will play together this season. Mathis looks forward to the damage the combination can create.

"They have to have at least two or three sets of eyes on him (Freeney) at all times, and I'd like to feel like I will draw a little bit more attention," he said. "You can't just single block him, and it helps me just as well as I feel like I help him."