PITTSBURGH — Tom Wilson’s aggression helped propel him from fourth-line grinder into a difference-maker who skates alongside Alex Ovechkin and Nicklas Backstrom.

His teammates feed off the edginess of his play. His coach loves his tenacity.

“There are very few Tom Wilsons in the league,” Barry Trotz said.

And in Game 4 of Washington’s increasingly prickly Eastern Conference semifinal against Pittsburgh, there might not be any at all.

The league is weighing whether to discipline Wilson for his run-in with Penguins forward Zach Aston-Reese that left the rookie with a concussion and a broken jaw.

Aston-Reese was skating in front of the Washington bench when Wilson’s left shoulder hit some combination of Aston Reese’s shoulder and jaw in the middle of the second period.

Following a brief conference among the on-ice officials, Wilson was not penalized on the play and the Capitals used it as a rallying point on their way to a dramatic 4-3 victory that gave them a 2-1 series lead.

The league, however, called for a hearing to take a closer look, forcing the Capitals to face the prospect of attempting to push the two-time defending Stanley Cup champions to the brink of elimination without one of their most physical players.

Trotz defended Wilson, who has now been disciplined by the department of player safety three times this season.

“It was a collision,” Trotz said Wednesday before the suspension was announced. “They hit and to me it looked like body on body. We’ve stopped it, we’ve looked at it, there’s pictures all over the Internet that you can see. He doesn’t leave his feet. It’s body-on-body. . I’m surprised the player has the injury that he has.”

The hit overshadowed the kind of taut and electric play that’s come to symbolize one of the NHL’s top rivalries.

Sidney Crosby gave the Penguins the lead with a goal late in the second period only to have Washington — in a historically un-Washingtonlike move whenever the Capitals face Pittsburgh — beat Matt Murray twice in the third to win, the last coming on Ovechkin bunting in a rebound of his own shot with just 1:07 to play.

“I really believe this year has felt a little bit different,” Washington forward Jay Beagle said. “Even in season when we would get down a couple goals we could fight back. It seems like we’re never out of it.”

Then again, it’s been 36 months since the Penguins have exited the postseason without the Cup on the team plane.

Pittsburgh has ripped off nine consecutive series victories during its run at the top, and has only trailed after three games once, in last year’s Eastern Conference final against Ottawa.

The Penguins rebounded to win in seven games and there’s hardly any panic. It’s not what Pittsburgh does.

The other thing the Penguins try not to do? Get so caught up in trying to retaliate against Wilson that they forget why they’re out there in the first place.

Defenseman Kris Letang pointed to his team’s antagonist — and entirely legal — response to Wilson in Game 3 as proof.

Jake Guentzel delivered a shot into the end boards. Defenseman Jamie Oleksiak basically begged Wilson to fight, but didn’t take it too far when Wilson failed to engage.

“After the whistle we walked away,” Letang said. “There’s not much business to do. I liked our answer.”

The Penguins will need another one if they want to keep their hopes of becoming the first team in 35 years to three-peat alive. They’ve only dropped consecutive games in the playoffs five times in two-plus years and have lost to Washington only once in 10 all-time postseason meetings.

The Capitals have momentum on their side. Pittsburgh has history.

“It’s hard to win in the playoffs and you’re going to go through ups and downs and emotional highs and emotional lows,” Penguins coach Mike Sullivan said. “And it’s all about how you handle those and respond. ... Right now our eyes are on Game 4.”