BOSTON – Sidney Crosby and the potent Penguins have been punchless.

Pittsburgh led the NHL in scoring in the regular season. It averaged 4.27 goals per game in the first two rounds of the playoffs. And the Penguins poured in 13 goals in the last two games of the Eastern Conference semifinals.

Since then?

No addition necessary.

The Penguins have just one goal in two losses on their home ice to the Boston Bruins.

To play there again this season, they must win Wednesday or Friday and avoid what seemed so improbable just a few days ago — being swept in the best-of-seven conference finals.

“Right now, we’re not liking the picture, down 0-2. They’re in control,” Penguins Coach Dan Bylsma said. “I don’t think we’re frustrated by the fact that we haven’t scored as much as (the fact that) they’re getting up leads, especially in Game 2.”

The Bruins won the opener 3-0 but led just 1-0 after two periods. The second game was much different.

They rolled to a 4-1 lead after one period and remained aggressive in finishing off their 6-1 rout. The Penguins’ effort waned as the game went on.

“It felt like every time we had a puck that was bouncing, we ended up giving it away,” Crosby said. “We gave them the game. We didn’t really do anything to give ourselves a chance to win.”

Combine that with the Bruins’ high level of play — disciplined on defense, organized on offense — and the pre-series chatter about the Penguins being favorites seems like so much nonsense.

But any talk that Boston will have an easy path to the Stanley Cup finals is just as premature.

“We’re going to have to play even better than we did because they’re going to be desperate,” Boston’s David Krejci said.

With a day off to ponder their problems and work at eliminating them, the Penguins’ offense could resurface.

“It’s about what we do in the next game,” Boston defenseman Andrew Ference said, “not about patting ourselves on the back for what’s already happened.”

Both teams have overcome 2-0 deficits and gone on to win Stanley Cups.

“You don’t have a choice but to respect that team that you’re playing against, because they are a pretty potent team. Things can change pretty quickly in this game,” Boston Coach Claude Julien said. “I don’t think there’s any comfort level in our team right now.”

The Bruins have stymied the Penguins’ offense with pressure the length of the ice. A puck carrier gets past one forward then must contend with another, then a defenseman and, finally, Boston goaltender Tuukka Rask.

“I think it’s pretty obvious that we have layers,” Julien said. “Our guys are committed to come back and just making sure that there’s layer after layer that make it hard for them to get to our net.”

It’s been relatively easy for the Bruins to get to the Penguins’ goal, whether Tomas Vokoun or Marc-Andre Fleury is trying to protect it. Fleury replaced Vokoun after Krejci, the NHL postseason leading scorer, gave Boston a 3-0 lead at 16:31 of the first Monday night.

“We gave up the first goal both games and, from there, everyone is trying to do it on their own,” Vokoun said, “it’s just not going to work.”

Bylsma hasn’t said who will start Wednesday.

“I think there’s going to be some changes to our lineup,” he said, “and some of our combinations, our lines.”

No need for the Bruins to change anything.

All four lines have been productive. The defensive pairings have been strong. And Rask has been outstanding, stopping 55 of 56 shots in the series.