It’s the day before the playoffs begin — a Capitals postseason that remained in doubt until a week ago — and every player on the ice is hydroplaning at game speed. As final prep for the defending Stanley Cup champions in Boston goes, it’s so fast and intense.

Alexander Semin is checked into the glass, his contorted face pressed within three inches of your eyes. A penalty-killing simulation feels like the real deal as the puck is blasted into the boards at upwards of 80 mph.

But the biggest difference between now and 2009 to 2011? The smiles. They’re everywhere. The ease in their steps as they leave the ice. From 20-year-old Cody Eakin, who would die happy if he got his first NHL playoff shift, to Mike Knuble, a proud captain trying to play his way back onto a line at 39, it seems contagious.

Everybody who remembers the past three years before Game 1 of the first round says the mood was lighter this time, the locker room more jovial. No President’s Trophy to validate like in 2009. No chance of Barry Melrose or Don Cherry proclaiming on television, “Without a doubt, the Washington Capitals will be raising the Stanley Cup come June.”

No pressure this time. Just playoffs, something no one around here takes for granted anymore.

“We’re not going in as one of the No. 1 seeds like the Caps have been the past few years, that’s true,” Matt Hendricks said. “But we still have high expectations of ourselves in here, this group. We feel like we’re a team that can vie for the Cup. And that’s our goal.”

Added Jay Beagle: “I don’t really consider us an underdog. Especially going into this series, just because we did well against Boston this year. I know it’s regular season and now it’s playoffs. But you know, I don’t really consider us underdogs. Obviously with the regular reason, with the ups and downs, we didn’t finish where we wanted to finish. But it’s a whole new season now.”

This must be what it feels like to play with house money in April. This must be what Montreal felt in 2010 when it pulled off a shocker over top-seeded Washington en route to meeting the seventh-seeded Flyers in the all-Cinderella Eastern Conference finals.

Hey, if it can be done anywhere in big-revenue North American team sports, it can be done in hockey.

Just three times in the last 11 years has one of the NBA’s No. 1 or 2 seeds been upset in the first round. That’s the extreme, but in general the best regular season teams often advance to the conference finals or league championship and almost always the next round. Except in hockey.

In the NHL playoffs, monster upsets are the norm. In the last 11 years, only three times have hockey’s No. 1 and 2 seeds on each side of the bracket made it out of the first round unscathed. Beyond the Caps in 2010 and 2000, when they were seeded second and lost to the No. 7 Penguins, Ottawa, San Jose and Detroit have been stunned as No. 1 or 2 seeds in the postseason.

Since 1990, the NBA has had just eight champions. During the same time frame in the NHL — minus a year for labor stoppage — there have been 14 champions and just two back-to-back winners, the Penguins in 1991 and 1992 and the Red Wings in 1997 and 1998.