Brandon Prust of the Rangers collides with Mike Green and...

Brandon Prust of the Rangers collides with Mike Green and Braden Holtby on a breakaway in the third period. (April 7, 2012) Credit: David Pokress

The Rangers figured they'd be playing the first round of the postseason in the nation's capital.

Wrong nation.

Bring on . . . the Ottawa Senators.

A win over Washington at Madison Square Garden in the season finale Saturday night would have pitted the Rangers against the Capitals in the first round of the Stanley Cup playoffs.

Instead, the Capitals moved up to the seventh seed after blitzing Henrik Lundqvist for three first-period goals in a 4-1 win.

The Florida Panthers, another possible first-round opponent for the Rangers, beat the Carolina Hurricanes to clinch the Southeast Division and the No. 3 seed in the Eastern Conference.

So the Rangers, the top seed in the East, will face eighth-seeded Ottawa (41-31-10, 92 points), which has lost three in a row. The Rangers (51-24-7, 109 points), who have lost two in a row, won only one of four games against the Senators (3-2 in Ottawa on Nov. 9).

With a victory, the Rangers would have clinched the President's Trophy, awarded to the team with the most overall points. After losing, they had to wait long past midnight to learn that they had been beaten out by the Western Conference-leading Canucks, who finished with 111 points by defeating Edmonton, 3-0. The Rangers won the trophy in 1991-92 and '93-94.

"You want to nail it down,'' defenseman Marc Staal said. "We didn't. It's disappointing."

"We were looking forward to the playoffs maybe a little too much," Brad Richards said. "We're going to come out with energy and emotion. We've played this style all year -- the level will have to go up." He called Ottawa "a very offensive team and very opportunistic."

The Rangers' first two playoff games are at the Garden on Thursday and Saturday. "There's a big trophy at the end of the line," Dan Girardi said. "Everyone realizes what we have ahead of us."

The Senators beat the Rangers, 5-4, in a shootout Oct. 29 in the Blueshirts' second home game of the season. Richards scored twice and Marian Gaborik and Ryan Callahan once each. Five games later, Gaborik scored twice and Derek Stepan once in the Rangers' 3-2 win. In the third game in the series, the Senators earned a 3-0 win at the Garden Jan. 12. The last meeting was March 8 in Ottawa, with Callahan scoring the Rangers' lone goal in a 4-1 loss.

The Capitals scored on their first two shots Saturday night. Brooks Laich won a faceoff from Stepan and got the puck back to Alex Ovechkin, whose 40-foot shot from above the left circle flew past Lundqvist only 32 seconds into the game. At 2:18, Mathieu Perreault, standing in front, tipped in Roman Hamrlik's point shot for his 16th goal.

"Everything that could go wrong in the first period did," Lundqvist said. "The puck just seemed to go their way."

After killing Richards' hooking penalty, the Rangers couldn't survive a second whistle after Ryan McDonagh cleared the puck into the stands for a delay of game at 16:41. John Carlson's long shot appeared to hit Artem Anisimov and change direction.

Nicklas Backstrom made it 4-0 at 5:58 of the second -- the fourth goal in 10 shots -- before Brian Boyle's 11th goal, on a wraparound from the left side at 12:44, got the Rangers within 4-1.

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