Think twice before making plans for Friday night. The Bruins just might be taking the ice that evening.

Presented with their second chance to eliminate the Flyers, the B’s took a few big strides in the wrong direction Monday night, dropping a 4-0 contest to the Flyers in Game 5 of the Eastern Conference semifinals at TD Garden.

Boston still leads the best-of-seven series, 3-2, and a favorable bounce of the puck in Game 6 in Philadelphia Wednesday could still let the Bruins avoid a Game 7 scenario back at the Garden Friday. But there is plenty to be improved upon in the next few days. 

“They were better than us tonight, it was a good lesson for us, they came in here and slapped us in the face,” said Bruins forward Mark Recchi. “Now we have to go there and realize this is a series now.”

You can’t fake desperation, and the Flyers simply skated like a team on the verge of elimination in Game 5, while the Bruins struggled to get in gear. Simon Gagne had a pair of goals, Ville Leino and Scott Hartnell single tallies as Philadelphia built upon a 5-4 overtime win in Game 4.

There was little right with the Bruins play Monday. They struggled to clear the defensive zone, failed to launch quality shots at the Flyers net and lost the special teams battle, a problem exasperated by an uncharacteristic propensity to take bad penalties.

In short, the Bruins really weren’t skating like a desperate team. Perhaps they ought to be. Trends don’t necessarily carry over in the playoffs, but a Bruins team built to lead with defense has given up nine goals in the last two games and the Flyers have found a huge burst of momentum.

“I don’t know if we were a little bit nervous, it’s hard to explain, to find words for it,” said captain Zdeno Chara. “We didn’t play with the composure we were playing with.”

On Monday, a steady parade to penalty box undermined the Bruins ability to grab momentum, but they also were not sharp in their own zone. While Tuukka Rask was in top form at times, he still yielded three goals on the first 17 Flyers’ shots. Philadelphia is averaging better than three goals a game in the series and Rask’s save percentage has dipped to a pedestrian .907 mark against the Flyers in the postseason.

“We were not sharp in their end in front of the net or in our end. We have to get better than that,” said Rask who suffered his first back-to-back losses since early February. “They made some good plays and scored some goals.”

While Rask maybe coming back to earth after his impressive rookie season, the Flyers had their own goaltending issues, as Michael Leighton had to jump into his first action since March 16 after starting goalie Brian Boucher suffered a left leg injury and had to leave the game 4:35 into the second period.

Trailing 1-0 at the time, the Bruins immediately went on a power play but failed to test Boucher’s replacement.

“That was a huge disappointment,” said center Marc Savard. “Especially when he comes in with 15 minutes left [in the second period] and maybe one or two shots on that period. So that’s obviously terrible.”

Let off the hook by the Bruins, Boucher (9 saves) and Leighton (14 saves) became the first NHL tandem to share a playoff shutout against Boston since Montreal goalies Jacques Plante and Charlie Hodge combined to beat the Bruins 2-0 on March 22, 1955.

On a day when the team unveiled a statute memorializing Bobby Orr’s Stanley Cup winning goal in 1970, the Bruins have suddenly left their current fans wondering if anyone under age 40 will be able to share the experience of seeing a real, flesh-and-blood Bruin play for the Cup for the first time in their lives this season.

The Bruins remain one win away from their first trip to the conference finals since 1992, but the Flyers have significant momentum.

“They are playing with desperation and that attitude of no quit, no one is going to stop them,” said Milan Lucic. “They are a confident team right now. We have to play more like them.”

Philadelphia has benefited from one obvious swing in personnel in the last two games, as the Bruins skate without center David Krejci (season-ending wrist injury) while the Flyers have benefited from the return of Gagne, who has three goals in two games, including the overtime winner in Game 4.

Although much of the focus has been on the loss of Krejci’s offensive contributions, his defensive presence is equally important to the Bruins.

“He obviously has a lot of offense upside to him but I think (because of that) people underrate his defensive zone play,” says Lucic. “He plays a lot of minutes for us and we miss him, but that shouldn’t be an excuse at all. We expect guys to bring their game up and step in when a guy goes down like that.”

There is still plenty of reason for the Bruins to be optimistic that they can close the series out Wednesday. Road teams still have a 36-34 winning edge this postseason and the B’s have already shown they can play effective, winning hockey in Philadelphia.

Erasing memories of Monday’s Game 5 disaster may be the first order of business.

“We still lead the series, we have to get ready mentally and physically for the next game,” said Chara. “We know it’s going to be really tough but we have done it in the past. Certainly we believe we can do it.”

The answer may be as simple as getting back to desperate hockey.

“We have to a better job of applying the pressure rather than feeling it,” said Lucic.