Washington Capitals left wing Alex Ovechkin checks New York Rangers center Brian Boyle. (John McDonnell/THE WASHINGTON POST)

The Washington Capitals may have a two-games-to-none lead in their Eastern Conference quarterfinal series against the New York Rangers, but there’s no sense of accomplishment yet from a team that has experienced postseason letdowns before.

“What is two games anyway? Nothing,” veteran right wing Matt Bradley said. “We know better than anyone how a team can come back and win three, four games in a row. No matter what lead you have, there’s no guarantee.”

The matchup shifts to Madison Square Garden for Game 3, a Sunday matinee that provides the Capitals with a chance to seize a stranglehold on the series and back the Rangers into a corner. Those stakes simply reinforce to the Capitals that they can’t afford to give New York a glimmer of optimism about its fate in this series.

Historically, NHL teams have held a 2-0 lead in a best-of-seven postseason series 307 times and only coughed up that advantage on 41 occasions. Washington, though, hasn’t fared as well as the rest of the league.

In their 21 previous playoff appearances, the Capitals have led a series 2-0 eight times and are 3-5 in those rounds. Three of those instances, including two series wins, occurred in best-of-five setups. In best-of-sevens, they are 1-4, with the lone win coming in 1997-98 with a five-game round against the Ottawa Senators in the Eastern Conference semifinals.

This is only the second time under Coach Bruce Boudreau that Washington has ever established the two-games-to-none advantage. The prior instance came in 2009 against Pittsburgh, an eventual seven-game loss in the Eastern Conference semifinals.

Past records aren’t something that Washington puts much stock into anymore, though, not after relinquishing leads in consecutive postseasons to the Penguins in 2009 and the Montreal Canadiens, who trailed 3-1 in 2010.

Each of those disappointing exits serve as warnings to this year’s club of how critical it is for the Capitals to finish an opponent off as efficiently as possible and maintain a high standard of play for themselves.

“I think last couple years when we get the lead, we’ve felt like series is done,” captain Alex Ovechkin said, “and team is just a little bit calm, a little bit relaxed and they play much better than us and win the series. Right now, this team is different. That kind of experience to have couple years helped.”

The difference in perspective was evident in the dressing room after Washington’s 2-0 win in Game 2 on Friday at Verizon Center. To a man, the players were more concerned with how much time they spent playing in the defensive zone in the third period, giving the Rangers plenty of territory and opportunity to come back — even if New York only mustered six shots. That the Capitals had earned a two-game lead in the series seemed like only a side note to the larger issue of their imperfect play.

“It feels good to be up 2-0, but we’re going into a tough building and every game has been a bounce here or there, and that’s been the difference,” forward Boyd Gordon said. “By no means do you get comfortable in the playoffs.”

While Washington wants to avoid complacency, the team doesn’t want to overhaul what has made it successful in the past two games. To earn this lead, the Capitals have played the patient, defensive style that pushed them to the top seed in the Eastern Conference — but with bite. Washington brought its physicality and has outhit the Rangers 70-69 and bested them at their trademark shot-blocking (53-43). Those fundamentals can’t change, the Capitals said, but even then, there’s no way of knowing what exactly is required to close out a series.

“I wish I had the crystal ball to say, ‘Okay, this is what we have to say or do so we don’t lose the next game,’ ” Boudreau said. “We want to play very similar to what we’re doing, but only better. Because we feel every game, we have to get better. We know the Rangers will get not only better, but as time comes on it’ll be more desperate.”