There is a premium on fast knock-outs as the Stanley Cup playoffs open tonight. To avoid the stigma of hockey in June, the NHL has decreed grueling back-to-back competition in both the best-of-five first round and the first four games of the best-of-seven quarterfinals.

Accordingly, a team forced to the first-round limit would be playing nine games in 13 days. Throw in some coast-to-coast travel and the setup defies reality.

The eventual winner figures to be the team that can end its early series quickly, saving strength for the big games in May. The pick here, as it was in September, is Buffalo.

Although building availability forced some minor changes, the basic first round format calls for Tuesday and Wednesday games at the team highest in the standings, Friday and Saturday at the other city, and a Monday return if a fifth game is necessary. Edmonton at Philadelphia

After posting that incredible 35-game unbeaten streak, the Flyers stumbled and won only three of their last 13 contests. Their big edge on the Oilers is their ability to throw in fresh bodies for those back-to-back ordeals. Vancouver at Buffalo

The Sabres were unbeaten in their last 14 games to finish second. Buffalo goalies Don Edwards and Bob Sauve shared the Vezina Trophy as the Sabres allowed only 201 goals, 33 fewer than the nearest challenger. Hartford at Montreal

The Whalers gave the Canadiens fits this season, tying three games while losing only one. Blaine Stoughton, a 56-goal scorer, carries a hot stick into the playoffs. Some of the older Whalers will find the tight scheduling very difficult, however. Pittsburgh at Boston

Boston will be without goalie Gilles Gilbert for the playoffs and the scheduled puts a terrific burden on Gerry Cheevers, with Yves Belanger a mediocrity at best. Each team beat the other twice on the road this year. Los Angeles at New York Islanders

The Kings have the scoring champion in Marcel Dionne, 137 points with 53 goals, but they yielded 313 and cannot hope to match up with the tight play of the Islanders. New York has been its old self since Denis Potvin returned. What the Islanders need is a quick kayo of the Kings and the upset of one of the top four, so that they would not have to face the Bruins in the quarterfinals. Toronto at Minnesota

The teams divided the season series along home-ice lines. This is only the second playoff appearance from Minnesota in seven years, while the Leafs have a history of coming up bit at playoff time. There is a good upset possibility here. St. Louis at Chicago

Chicago is trying to end a record stiring of playoff defeats that has reached 16 games. The Blues won the season's series, 2-1-1, and it was evidence of the Hawks' fear of them that they pulled the goalie in a tied game Sunday to try to get the extra point that would have paired them against Toronto. Atlanta at New York Rangers

This is the choice first-round pairing and lends promise of an upset, since the Rangers have not beaten Atlanta in their last seven meetings.