The last team to win a Stanley Cup playoff series from the Montreal Canadiens was Buffalo, in the 1975 semi-finals. As the NHL's second season begins tonight, the Sabres once again are a primary threat, but a Tuesday defeat by the Washington Capitals has diminished their chances.

Buffalo, with three victories over Montreal, finished the regular season with 105 points, the same total as Philadelphia. The Flyers won one more game and, because playoff pairings are determined by season records, they would enjoy home-ice advantage against Buffalo should the teams follow form into the quarterfinals.

The winner of the series, again barring upset, would be paired with Montreal, which has the home-ice edge in all series in which it participates.

The Canadiens, realistically, have every other kind of edge imaginable. Their goalies, Ken Dryden and Bunny Larocque, shared the Vezina Trophy as the NHL's best. Guy Lafleur collected 132 points to earn the Hart Trophy as league-leading scorer for the third year in a row. Montreal also has the biggest, most mobile defense in the NHL.

Still, eight teams will begin best-of-three preliminary action tonight with hopes of drinking from the Stanley Cup. Montreal and fellow division winners Boston, Chicago and the New York Islanders await the survivors in best-of-seven quarterfinal action opening Monday. Here is the outlook for the preliminary games, scheduled Tuesday, Thursday and, if necessary, Saturday: