The Montreal Canadiers, concerned by the lack of time to prepare for the Boston Bruins, held an unusual 30-minute meeting before tonight's opening game of the Stanley Cup final. Then they went out and thrashed the Bruins, 7-3.

Wingers Yvon Lambert and Mario Tremblay each scored twice and center Doug Risebrough added one, for a five-goal contribution from a line that had totaled only two goals in 10 previous playoff games.

"Against St. Louis we were playing really hard," Lambert said, "and against the Islanders we were doing our job, too. The one thing we weren't doing was putting the puck in the net. When you keep working, the results have to come, and I guess they came tonight."

Risebrough and Tremblay connected in the first five minutes and Boston never was able to pull even. The Bruins, however, trimmed a 4-1 deficit to 4-3 on second-period goals by Terry O'Reilly and Bobby Schmautz.

Boston had not played since Sunday, while Montreal had concluded a tough six-game series with the New York Islanders on the road Thursday night. The Canadiens vainly attempted to have tonight's game delayed until Sunday and it seemed logical to expect them to tire in the final 20 minutes.

Instead, the Canadiens simply blew the Bruins off the ice. Rick Chartraw, moved up from defense to right wing on a makeshift fourth line, made it 5-3 after only 59 seconds of the third period. Sixty-five seconds later, Lambert set up Tremblay's second goal and the result was beyond doubt.

"We just had one bad period," said Boston coach Don Cherry. "It's a history of our club that when we have four or five days off it takes us a while to get going. They got seven goals, what else can I say?

Cherry, who usually can laugh off a defeat, began the interview by retreating to a Forum wall, spreading his arms and saying, "Shoot." But his usual one-liners were missing and it was obvious he had hoped to get the jump tonight.

"Let's face it, they Canadiens must have been a little tired, but they played good," Cherry said.

"We didn't have much time to get prepared and it was a concern for us." said Montreal coach Scotty Bowman. "Anybody would have wanted to wait until Sunday. It just worked out for us."

"I'm sure we'll be a lot stronger Tuesday night," Lambert said. "We were maybe a little nervous, we didn't have time to pratice and we didn't have a really good metting about what to do against Boston."

Peter Mahovlich, who assisted on two boals, and Steve Shutt were unable to skate earlier today, but they played, and played well. Nahovlich has a bruised knee and Shutt a bruised shoulder. When the Canadians are rested and healthy, it is difficult to see how the Bruins can beat them four times.

The Bruins, outshot, 24-20 managed only three shots in the second period and scored on two. The first was a one-man show by Terry O'Reilly, who carried the pack into the slot, hung on against assaults by Larry Robinson and Serge Savard, shoved the puck to teammate Brad Park and deffected Park's shot into the net.

It was one of the few bright moments for the vocal Boston minority in the crowd of 17,311. For the most part, the Canadiens were outhustling the Bruins, and the hustle paid off on the scoreboard.

In the early moments, Lambert raced unchecked up the left wing, drew Park out of position, then passed to Risebrough, who cut behind Park to score. Not long after on a Montreal power play, Doug Jarvis dumped the puck into the corner and Robinson beat defender Mike Milbury to it. Goalie Gerry Cheevers, who had begun a move for the puck, tried to scramble back to the net, but Lambert had converted Robinson's perfect pass before Cheevers made it.

"We knew we had to do a very good job against Gerry Cheevers." Lambert said. "We beat him in those first few shots ad he looked nervous. He didn't make the key saves like against Philadelphia."

On a percentage basis, 17 out of 24, Cheevers did not make many saves at all.