Less than 24 hours after three teams were eliminated from the Stanley Cup playoffs, the Ottawa Senators sent the Boston Bruins packing on Sunday evening with a 3-2 win in the fourth overtime matchup of the series, and the Washington Capitals did the same against the Toronto Maple Leafs with a 2-1 OT win of their own.

With the first round of the postseason suddenly wrapped up, here are a few takeaways from Sunday night's series-clinching action:

The unlikely Senators are on the move and headed for a big challenge

The Senators' series-clinching victory was sealed by an unlikely standout in Clarke MacArthur (who scored the winner 6:30 into the extra period) and with some tight defensive play. But the Ottawa win followed some controversy earlier in the series, as goalie interference calls and other questionable calls left the Bruins -- and, perhaps more so, their fans -- feeling outnumbered.

Even so, Ottawa is on the move. The Sens proved they could knock off Boston in close fashion, relying on their defense. Ottawa notched a shutout win in Game 4 and three other one-goal victories.

That does not mean the road ahead will be any easier, however, as the New York Rangers moved past the Montreal Canadiens on Saturday night. Squaring off with New York's loaded offense -- which had its ups and downs taking on Carey Price and the Habs but remains a threat with some in-the-net dominance from Henrik Lundqvist -- figures to be a tad more difficult than dealing with Boston.

The Maple Leafs gave it their all up until the finish line

The Capitals kept the oddsmakers happy by securing a trip to the second round on Sunday night, and Marcus Johansson had himself a performance. But Toronto still warrants a hat tip or two for the series it played.

Between rookie sensation Auston Matthews coming on strong once again and Frederik Andersen making some highlight-reel saves in the net, the Maple Leafs may have had the more interesting night Sunday, especially considering they scored only one goal for the second consecutive game.

Just look at Matthews' shot on a favorable, albeit awkward, puck bounce to give Toronto a 1-0 lead in the third period of Game 6:

And check out Andersen's sly save that robbed T.J. Oshie of a score:

Combine those nifty plays with the fact that the Maple Leafs, severely overmatched in pure talent against the Caps, pushed Washington into OT five times and almost exclusively lost by only a single goal throughout the first-round series, and it's pretty clear that, even after the final results, Sunday's matchup proved Toronto belonged in the spotlight.

Unless, of course, you found Alex Ovechkin's cheap-shot payback, which darn near had a Maple Leaf piggybacking him, the highlight of Sunday's Game 6:

The Capitals are headed for the matchup we've been waiting for

That's right. It's happening.

The Pittsburgh Penguins have been sitting pretty ever since they knocked off the Columbus Blue Jackets in five games. And now the defending champions will get the chance to oust the Presidents' Trophy winners and much maligned playoff contenders in Round 2.

Seeing Matthews and the Maple Leafs go head to head with Sidney Crosby and his high-flying Pens would have been a battle worth the price of admission. But Pittsburgh and Washington are the Eastern Conference heavyweights we've all been waiting to see duke it out.