FOXBOROUGH, Mass. — Next man up.

The New England Patriots have lived by that slogan for years. A player goes down with an injury, a player gets traded or leaves via free agency, someone else has to step in.

Coach Bill Belichick has been a genius at finding the replacement parts.

Now he might have to pull a rabbit out of his hat.

The Patriots placed linebacker Jerod Mayo on injured reserve Wednesday following surgery to repair a right torn pectoral muscle. That means he’s done for the season, including playoffs.

Mayo, who has led the Patriots in tackles each of his five previous seasons (and was leading them again with 66 this season), was injured in the fourth quarter of Sunday’s dramatic 30-27 win over New Orleans. He tackled Darren Sproles and the two of them collided with New England safety Steve Gregory. Mayo got the worst of it.

His loss is compounded by the fact the Patriots have already lost defensive tackle Vince Wilfork for the season with a torn Achilles tendon. And defensive tackle Tommy Kelly missed Sunday’s game with a knee injury.

But Mayo’s injury and loss is more significant. He was the defensive signal caller. He was the team’s best pass coverage linebacker. He was a mentor to all the young players who stride through the locker room. Like Wilfork, he was voted a defensive captain at the beginning of the year.

No one person is going to replace him. No one person can replace him.

“We have a lot of leadership, I think, on this team, not just the guys who are appointed (captains), a lot of veteran guys that have been around a while that know what is expected of them and everyone else,’’ said left guard Logan Mankins. “We’ll miss Jerod but whoever ends up in that spot will do a good job.’’

Dont’a Hightower, a second-year linebacker from Alabama, suggested Wednesday that he will get the green dot on his helmet, signifying that he will be making the defensive calls.

He did it in college, leading the Crimson Tide to a national championship, so he’s confident he can do it again. Just don’t expect him to fill Mayo’s shoes.

“That’s something that I’m not going to be able to do,’’ he said. “I’m not Mayo. I’m Hightower. I’ve got to do my job.’’

That’s all the Patriots are asking, for whoever steps in to do his job.

It could be rookie Jamie Collins, considered the most athletic linebacker on the team but someone who has played sparingly this year. It could be fourth-year linebacker Dane Fletcher, who missed all of 2012 with a knee injury and is known mostly as a special-teams player.

It could be that Belichick and defensive coordinator Matt Patricia concoct some other scheme that will rely heavily on subpackages, with defensive backs filling Mayo’s role.

“It’s not going to be one specific person because you can’t do that with Mayo,’’ said Fletcher. “It’s got to be the whole defense that steps up.’’

They know this. Safety Devin McCourty said the defense will become a group of captains.

“When guys get hurt and they can’t be around, (other) guys have to step up,’’ said McCourty. “I’ve been appointed one of those guys to step up but it’s no different; guys on defense have to step up. Guys like (safety) Steve Gregory, who has played a lot of football here already. (Linebacker Brandon) Spikes, a guy who is a fourth-year player as well. We all have to step up and kind of be group captains now. You can’t replace two guys who have already been voted captains.’’

Quarterback Tom Brady was asked about handling the emotions of losing one of the team’s best players. He said, basically, that you can’t get emotional.

“You don’t want to feel sorry for yourself,’’ he said, sporting a bruise on his right cheek from a hit he took Sunday. “What you realize is somebody has to fill in and do the job. As much as you hate to lose guys, there’s nothing you can do about it and the season doesn’t end.

“You have to keep fighting on, just as they would want us to, just like they did when I went out (in 2008 with a knee injury), just like they did when guys like Rodney (Harrison) went out.’’

Brady then added, “Hopefully our execution on offense is better. That would take some pressure off the defense.’’

The Patriots’ offense has also been hindered by injuries. Tight end Rob Gronkowski has yet to play. Wide receiver Danny Amendola missed three games and may miss more after the vicious hit he took Sunday, knocking him out out the game. Running back Shane Vereen is on the short-term IR (which is why the Patriots couldn’t use that designation on Mayo).

But the defense has been hit especially hard lately, with Mayo and Wilfork gone, and cornerback Aqib Talib (perhaps the team’s MVP thus far) hampered by a hip injury he suffered against the Saints. Talib wasn’t present at the start of practice Wednesday.

The defensive injuries have hit the Patriots’ leadership more. Wilfork and Mayo were admired by the younger players for their willingness to teach.

Now the question becomes, who takes their place?

“Only time will tell,’’ said Mankins. “Someone has to.’’

Mike Lowe can be contacted at 791-6422 or at:[email protected]Twitter: MikeLowePPH

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