Pittsburgh squared the score on a power play just over three minutes later, tying it up on a Jake Guentzel goal at 7:27, but 33 seconds after that, the Caps regained the lead at 3-2 on a sublime slap pass from Christian Djoos to Alex Ovechkin, who netted his second goal of the young season at the eight-minute mark of the first.
With Ovechkin's goal, the two teams had combined for five goals on just seven shots in eight minutes of play. Things settled down on the scoreboard for the rest of the first stanza, but the Caps had the better of the possession and territory. Pittsburgh struggled mightily to exit its zone in the first period, continuously turning it over and gifting the Caps with scoring chances, but Washington was unable to expand that lead.
In the middle frame, the tables turned. Now it was the Capitals who couldn't exit cleanly with consistency, but the Pens too advantage.
Just 30 seconds into the second, Letang tied it at 3-3, beating Holtby on the short side with a left point drive. The Caps responded quickly after each of the first two Pittsburgh goals, and they did so again here as John Carlson scored on a short side snipe off the rush at 3:54, giving the Caps their last lead of the night at 4-3.
Pittsburgh was able to retake the lead with a couple of extended offensive zone shifts where Washington got hemmed a bit and wasn't able to exit its end cleanly.
Guentzel notched his second of the night at 15:09, tipping a Justin Schultz point shot past Holtby to tie it at 4-4. Less than two minutes later, Derick Brassard corralled a rebound of a Dominick Simon shot, and had all the time and space needed to backhand it home from down low, putting the Pens up 5-4 at 16:58.
After limiting the Pens to five shots on net and 13 shot attempts in the first, the Caps yielded 23 shots on net and 35 attempts in the middle stanza. Were it not for a pair of dazzling saves from Holtby - a right pad save on Guentzel and a right arm stop on Bryan Rust - the damage would have been worse.
Penalty trouble - perhaps a by-product of fatigue and the early set of back-to-backs - also plagued the Capitals; they were guilty of each of the last five infractions in the game, with three of those coming in the first half of the third. Just after the expiration of one of those Washington penalties, Pittsburgh's Evgeni Malkin finished off a pretty tic-tac-toe passing play to give the Pens a 6-4 lead early in the third.
The subsequent Washington penalties mostly stalled the Caps' attack, but they were able to tie the game on the strength of two Oshie goals in a span of just 21 seconds. First, Oshie turned a blatant Malkin turnover into an instant goal, firing shot past Murray from the slot with 6:59 left to make it a 6-5 game. Twenty-one seconds later, he made a deft mid-air deflection of a Carlson shot, tying the game at 6-6.
But 19 seconds into the overtime session, Caps center Evgeny Kuznetsov was boxed for hooking Crosby, and 61 seconds later, Letang scored the game-winner on a blast through traffic from center point.