Three weeks ago, the Minnesota North Stars came to Capital Centre and blitzed the Washington Capitals 4-0. Ten days later, Minnesota fired both its coach and general manager, and now the North Stars are playing better than ever.

So, if the Capitals were relieved to see the Montreal Canadiens leave town after Friday's 8-2 lesson, there is no guarantee of success when they skate out to meet the North Stars tonight at 7:30. Indeed, with the Capital's annoying habit of playing up or down to the opposition, there isn't even a guarantee of a close game.

The new general manager-coach of the North Stars is Lou Nanne who, as a nonplaying player on Minnesota's last visit, was employed as the color man on the telecast to Minneapolis. In three games under Nanne's direction prior to last night's contest at Toronto, the North Stars beat Vancouver, rallied from a 3-0 deficit to tie Colorado and whipped the Flyers in Philadelphia for the first time in seven years.

"We just gave the players a few instructions," Nanne said by telephone from Toronto. "We had to get them believing in themselves. The're checking better, making more contact, and they're cutting off the passes in the neutral zone. Things are definitely going pretty good."

Nanne spoke of the North Stars' record as a "strange" one, and they have been tough to figure. Of 13 victories, two have come against Montreal and one each over Boston, Philadelphia, the New York Islanders and Buffalo.

"We've got the talent to play with anybody," Nanne said. "The problem is to get the guys concentrating on the game, playing solid, consistent hockey. Montreal can win a game with a bad night, but if we've having an off night we can't win."

Although he presently occupies a dual role, Nanne will be only the general manager next season.

"I'll be hiring a coach at the end of the year," Nanne said. "I'm coaching now for the three reasons. I want to see what kind of a coach is needed to motivate these guys. I want to be behind the bench to see how the players react. And the guys I want to coach are under contract."

When the North Stars decided to fire General Manager Jackie Gordon and Coach Andre Beaulieu, himself a midseason succesor to Ted Harris, Nanne was asked to prepare a position paper on what was needed to turn the team around. One item that was not highly praised was Beaulieu's policy of two-a-day practices.

"That was ridiculous, high-school stuff," Nanne said."There are only two reasons for it, conditioning and punishment. If guys are not in condition after 55 league games, they never will be. And punishing guys that way is like spanking a kid, except these guys are in their 20s. If discipline is difficult, you get rid of them. You motivate them or send them down."

Nanne, a player with the North Stars since their first season in 1967-68, would not seem qualified to jump into the general manager's job. How ever, he is highly esteemed by NHL officials, including Washington President Peter O'Malley, and the principal reason why the North Stars made their sudden move instead of waiting until next year was the fear Nanne would take a position somewhere else.

One of Nanne's first moves was to persuade the New England Whalers to turn loose defenseman Bryan Maxwell, the North Star's No. 1 draft choice of 1975, who was passed up then because of his big salary demands. The next target, possibly as soon as tonight's game, is defenseman Bill Butters, a University of Minnesota graduate who has been knocking heads for the Whalers.