"Green raises and drives his left arm into Connelly's head with significant force, making it the principal point of contact and causing it to impact the glass. This is a clear hit to the head," NHL disciplinarian Brendan Shanahan said Friday.
"When Green decides to commit to this check, Connolly already is bent over. Green sees Connolly in this position; he then slows down, waits, loads up and targets Connolly's head. We've taken into consideration that Green has been suspended once and fined once for a similar infraction during his NHL career. We have also noted that Connolly later returned to the game and played in the third period."
During the second period of the Capitals' overtime victory over the Lightning, Green delivered a hit to the head of Connolly while he was already being checked by defenceman Dmitry Orlov against the boards and behind the net.
Connolly stayed down for a while before being helped off the ice by training staff, but did return to the game for the Lightning. No penalty was called on the play.
This is Green's second suspension in his seven NHL seasons. Green sat out three games for an elbow to the head of Panthers forward Michael Frolik in 2010.
Green will not be eligible to return until March 16 when Washington plays at Winnipeg.