But the Caps never could get on track. Boston played fast all night while Washington was rarely able to generate any consistent northerly movement with the puck. Over a span of 18 minutes and 40 seconds of a game they needed to win - from midway through the first to nearly midway through the second - they failed to register a shot on net.
When Nic Dowd broke that drought by putting a puck on Boston goalie Tuukka Rask in the eighth minute of the second period, it was just the Caps' third shot on net of the night at 5-on-5, with all three of them coming from bottom six forwards. Washington's first shot on net from a top six forward at 5-on-5 came from Alex Ovechkin, a 47-footer at 13:32 of the second period.
By then, the Caps were down a goal. Dmitry Orlov was assessed a major penalty for an open ice hit on Boston blueliner Kevan Miller just seconds after Dowd broke the shot dry spell. And although further video review lightened Orlov's sentence to a double minor, Boston jumped out to a 1-0 lead on the ensuing power play when Brad Marchand scored at 8:00 of the second to stake the Bruins to a lead.
Marchand's goal was the seventh straight Boston goal from one of the Bruins' top six forwards.
Once again, despite a dismal second period, Samsonov kept the Caps close. Boston took a 1-0 lead to the third, the first time this series that the Bruins have owned a lead at any intermission.
The Bruins opened the third period with 1:45 worth of carryover power play time, and when David Pastrnak scored his first goal of the series with the extra man just 29 seconds into the third, Boston went up 2-0, the first multi-goal lead for either team in the series.
Thirty-four seconds later, the lead was 3-0. Jake Debrusk missed the net on a breakaway, but Boston got a membership bounce off the glass, right to the late-arriving Charlie Coyle, who backhanded it home at 1:03.
Washington had three power play chances in the third, and it finally broke through on the second of those at 4:54 of the third. Ovechkin's one-timer from his office shattered his stick and bounded into the net off a Boston defender's skate to make it a 3-1 game.
That was as close as the Caps got. Boston's Matt Grzelcyk closed out the scoring with the Bruins' third power-play goal of the game at 14:50, a one-timer from the right circle.
"All facets solid," says Boston coach Bruce Cassidy of his team's effort and performance in Game 4. "Obviously, special teams speak for themselves. We gave up a goal there on a late power play that went in off our guy, so structure was excellent. We had some big blocks on Ovechkin. We kept some pucks out of the bumper with pressure, appropriate pressure.
"On our power play, we made a few adjustments and tonight they paid off. We got some shots we wanted. At 5-on-5, boy we didn't give up much. We protected the neutral zone well against a good transition team."
Suddenly staring at the possibility of a third straight first-round exit, the Caps have no more margin for error.