Sidney Crosby has been diagnosed with a concussion following a hit to the head delivered by Washington Capitals defenseman Matt Niskanen in Game 3, Pittsburgh Penguins head coach Mike Sullivan announced Tuesday.

Crosby will miss Game 4 and will be evaluated from there, Sullivan added.

"(Crosby is) very upbeat and positive," Sullivan said. "We're very optimistic and hopeful we'll have him back in a timely fashion."

Niskanen will not face any further discipline after being assessed a major penalty and a game misconduct at the time of the incident.

Crosby missed the opening six games of the regular season due to a concussion. In eight playoff games to date, he'd recorded four goals, seven assists, and 21 shots.

Game 4 is set for Wednesday in Pittsburgh with the Penguins holding a 2-1 series lead.

Copyright © 2017 Score Media Ventures Inc. All rights reserved. Certain content reproduced under license.