If Montreal's super scorer Guy Lafleur thinks his team's first National Hockey League game this season was the toughest he'll have, there would seem to be little point in his opponents playing the other 79 contests.

Although pressed somewhat during the first two periods-plus, the two-time defending Stanley Cup champion Canadiens powered home three goals in the final 14 minutes to grab a 7-3 decision over the young Minnesota North Stars.

Lafleur, the NHL scoring champ last season with 136 points on 56 goals and 30 assists, picked up where he left off - which was with a 28-game regular-season scoring streak - with two goals, including the game-winner.

"Flower" scored at 14:12 of the opening period on a power play to give Montreal a 2-1 lead and fired in his second tally 1:42 into the third session.

"The first game is always the toughest," he said. "It takes a little while for you to reach your full capacity. I think there's a lot of room for improvement. Even though I scored twice, our line did not control the puck as well as we can. But I'm sure there'll be some improvement as the season progresses."

Minnesota coach Ted Harris, who saw his team take a 1-0 lead, has no doubt the Canadiens will improve. "They probably won't lose more than one game all season," he said.

The Canadiens crusied through a record-setting seasion in 1976-77 with a 60-8-12 record and lost only two of 14 games in the Stanley Cup playoffs.

Minnesota's Nick Beverley and Montreal's Dough Risebrough traded first-period goals before lafleur's first marker, Rooke Pierre Mondou then gave Montreal a 3-1 first-period lead with his first NHL tally.

The North Stars' Pierre Jarry got the lone second-period goal to narrow Montreal's lead to 3-2, but Lafleur went around the Minnesota defense for the eventual winner early in the third session.

Roland Eriksson again narrowed Montreal's margin to one goal when he intercepted a Bill Nyrop pass at 2:52, but Doug Jarvis, Guy Lapointe and Yvan Cournoyer, playing his first regular-season game since a back operation last season, closed the door on Minnesota with third-period goals. Penguins 4, Blues 2

Jean Pronovost celebrated his recent selection as Pittsburgh team captain by scoring two goals, including the game-winner at 19:09 of the second period. Brian Spencer and Greg Malone rounded out the Penguins' scoring, while Garry Unger and Rick Bourbonnais scored for St. Louis. Rangers 6, Canucks 3

Phil Esposito scored one goal and added three assists to move into fifth place on the alltime NHL assist list with 740 as New York handed coach Jean-Guy Talbot a victory in his debut. Mike Walton had two of the three Vancouver goals. Kings 2, Barons 0

Marcel Dionne and Ernie Hicke each scored a goal and assisted on the other's tally and Glenn Goldup assisted on both Los Angeles goals as one line accounted for all the scoring. Rogatien Vachon stopped 24 shots for the shutout over Cleveland. WHA

Rusty Patenaude scored twice to help the Indianapolis Racers overcome a four-goal effort by Cincinnati center Richie Leduc and beat the Stingers, 5-4 . . . Tom Webster netted two New England goals and Whalers' goalie Al Smith recorded his eighth WHA shutout as New England beat Houston, 3-0. Bobby Hull scored once in each period to pace the Winnipeg Jets, who exploded for five third-period goals to beat Edmonton, 7-3.