NEW YORK -- When Ottawa Senators coach Guy Boucher was asked how defenseman Erik Karlsson had done what he had done, leading the Senators and performing at an all-world level playing with two hairline fractures in his foot, Boucher could only answer honestly.

Karlsson has, in some ways, seemed to will the Senators into the Eastern Conference Final, finishing off the New York Rangers with the game-winning goal in Game 6 at Madison Square Garden on Tuesday. He has been the best player on the ice in nearly every game, completing seemingly impossible passes and setting up unlikely goals.

But that does not erase the fact Karlsson is playing injured. Every moment he gets to rest is crucial for him and for the Senators. That's why it was so important they won Tuesday, ending the series before it got to Game 7 in Ottawa on Thursday.

That gives the Senators one more day of rest than their opponent, the Pittsburgh Penguins, who defeated the Washington Capitals 2-0 in Game 7 at Verizon Center on Wednesday.

"I think every day matters for us," Boucher said.

Video: Reactions to Senators beating the Rangers in Round 2

Not that Ottawa is alone in that regard. But for a team that relies as heavily on Karlsson as the Senators do, it might matter more to them than perhaps anyone else in these Stanley Cup Playoffs.

"I've lived it before," Boucher said. "I think there's a lot of emotion in the first round. Teams are mostly healthy in the first round and excited and have got a lot of energy. But then you start seeing in the middle of the second round, every game there's more guys banged up, more guys tired. There's a mental, physical and emotional wear-down.

"But I think it's nothing like the third round. If I remember correctly, it was really tough once you get to the third round and I think a few days rest definitely makes a big difference. Rest is a weapon."

It's a refrain Boucher has used through the first two rounds, often to refer to the fact the Senators rarely practice and he prefers to remain in a city overnight after a game, rather than flying out late.

Boucher also seemed to make it clear how important rest was for the Senators and for Karlsson when he held the Ottawa captain out of the third period of Game 4 against the Rangers, a game the Senators lost 4-1. Instead, he thought giving Karlsson the time off the ice would bring him back better in Games 5 and 6, both won by Ottawa.

Video: Clutch Performance: Karlsson continues to perform

"I think that everybody's going through things at this time of the year," Karlsson said. "We're doing a good job in helping each other out. The burden doesn't lay on certain people. They're spreading it out and everybody's doing their job and making it easier for each other. It's never going to be easy this time of year."

That's why the Senators need to take the gift they've given themselves and use it to their full advantage. They need to rest, they need to get better and stronger and recharge, to ready themselves for yet another series when they'll be the underdog. They need to take a break from the mental stress, the pressure, give themselves time to decompress.

That was why defeating the Rangers in Game 6 meant so much to them, in addition to advancing to the Eastern Conference Final, a place few expected them to reach.

"We knew coming in here we had to get this done tonight," forward Clarke MacArthur said Tuesday. "First off, you obviously don't want to chance Game 7 with [the Rangers]. Second of all, even if you win that next one, you roll right into the lion's den, the next round. You've got no break, no time to heal little injuries. Now we've got that. We have to make the most of it."