Pittsburgh Penguins star Sidney Crosby will miss Game 4 with a concussion.

"Sid has been diagnosed with a concussion," Penguins head coach Mike Sullivan told reporters. "He will be out for tomorrow's game. We will evaluate him from there."

Crosby suffered the concussion in the first period of the Washington Capitals' Game 3 overtime win, when he was cross-checked by Capitals defenceman Matt Niskanen as he was cutting across the net.

Niskanen will not be disciplined for the hit.

Sullivan said Crosby is upbeat after the injury. "He's very upbeat and positive. We're very optimistic and hopeful we'll have him back in a timely fashion."

Sullivan also told reporters Conor Sheary has been diagnosed with a concussion as well.

Crosby has four goals and seven assists through eight games this postseason.

The Penguins lead the Capitals 2-1 in their second round series.

I canvassed a number of NHL head coaches and GMs today for their view on the Niskanen on Crosby hit. So far 23 of them have responded.... — Pierre LeBrun (@PierreVLeBrun) May 2, 2017

First reaction from the majority of them was expressing genuine concern for Crosby's health. Having said that ... (con't) — Pierre LeBrun (@PierreVLeBrun) May 2, 2017

Of the 23 coaches/GMs I've heard from, only 6 of them believe Niskanen should be suspended while one was on the fence — Pierre LeBrun (@PierreVLeBrun) May 2, 2017

Majority of the GMs/coaches polled felt there wasn't intent by Niskanen on the play; others pointed out that Crosby was falling (con't) — Pierre LeBrun (@PierreVLeBrun) May 2, 2017

However, 6 of them did feel Niskanen should be suspended, some felt he knew what he was doing; others because a head shot is a head shot — Pierre LeBrun (@PierreVLeBrun) May 2, 2017

Should also mention that several of the coaches/GMs questioned felt Alex Ovechkin should have been penallized for his slash on Crosby — Pierre LeBrun (@PierreVLeBrun) May 2, 2017

But again, for the most part, the majority felt the call on the ice vs. Niskanen was the right one but nothing more needed... — Pierre LeBrun (@PierreVLeBrun) May 2, 2017

Update: the coach who was on the fence says he's for a one-game suspension now that Penguins announced Crosby is out with a concussion — Pierre LeBrun (@PierreVLeBrun) May 2, 2017