PITTSBURGH — Pittsburgh Steelers defensive end Cam Heyward has embraced his role as a leader over the last few seasons, filling a void left by the retirements of Brett Keisel, Casey Hampton and Aaron Smith. He’s become a voice of reason in the locker room and a mentor to youngers Stephon Tuitt and Javon Hargrave.

Now it’s time to see if the kids can make it on their own.

Coach Mike Tomlin declared Heyward out for Sunday’s game at Miami, thanks to a left hamstring injury, meaning the Steelers (4-1) will play without Heyward’s familiar No. 97 in the lineup for the first time since he was taken with the 31st overall pick in the 2011 draft.

Heyward was injured in the first half of last Sunday’s 31-13 win over the New York Jets and underwent an MRI to determine the extent of the damage. Tomlin declined to get into specifics about how much time Heyward might miss, though the chances of him returning by an Oct. 23 showdown with New England seem bleak.

“He doesn’t fall in the realm of what’s normal in everything he does,” Tomlin said.

Making Heyward difficult to replace for a variety of reasons. His three sacks led the team, all of them coming in a romp over Kansas City on Oct. 3 following a whipping in Philadelphia that Heyward blamed almost entirely on the defensive front. He responded with the best statistical game of his career. Tomlin hinted it’s unlikely the Steelers will use just one player in Heyward’s spot, likely rotating out Hargrave, a rookie, and veteran Ricardo Matthews.

Hargrave, drafted as a nose tackle, spent time on the end against the Jets, with positive results, while Matthews impressed Tomlin with his aggressiveness.

“He’s got a motor,” Tomlin said. “He’s highly conditioned for a guy of his size.”

Perhaps, but the role of communicator along the line will fall to Tuitt. Now in his third year, he’s reveled in being mentored by Heyward.