As usual, the best-of-five opening round of the Stanley Cup playoffs has produced some surprising casualties. Minnesota, a Cup finalist a year ago, already has been eliminated, and the two-time champion New York Islanders tonight face a must-win situation for the first time since they were ousted by the New York Rangers in the 1979 semifinals.

This round may also have set a precedent in owner motivation, as both Edward DeBartolo Sr. of Pittsburgh and Jerry Buss of Los Angeles have directly influenced the resurgence of their clubs.

DeBartolo refused to attend the third game of the Penguins' series against the Islanders, because he was so disgusted with the team's effort in two straight losses on Long Island.

Pittsburgh responded with an overtime victory Saturday, then thrashed the Islanders, 5-2, on Sunday. So tonight at Nassau Coliseum a club with a 31-36-13 regular-season mark has a chance to eliminate the team with the NHL's best overall record, 54-16-10.

If there were any negative factors in the Penguins' situation, they could be traced to attendance at the Civic Arena. Apparently, a lot of folks accepted DeBartolo's invitation to turn in tickets, because the crowds were only 14,310 and 11,147 for the two games.

There were no empty seats at the Los Angeles Forum Saturday night, where Buss, angered when his Kings fell behind Edmonton, 5-0, after two periods, chewed out the players and walked out of the building.

Los Angeles rallied with five goals, tying the game on Steve Bozek's score with five seconds left, and then beat the Oilers in overtime, 6-5, before losing last night, 3-2. That left the Oilers, with the NHL's second-best record at 48-17-15, needing to win tonight in Edmonton to advance to the Smythe Division final against Vancouver.

The Montreal Canadiens, No. 3 in the regular season with a 46-17-17 record, are not home free, either. They must beat Quebec tonight at the Montreal Forum to advance to the Adams Division final against Boston.

The Nordiques had a 2-1 series lead and home-ice advantage Sunday, but the Canadiens were able to square things with a 6-2 triumph, only their second success in Le Colisee.

Everything was scrambled in the Norris Division, where fourth-place Chicago ousted Minnesota in four games and third-place St. Louis did the same to runner-up Winnipeg.

The North Stars, the surprise team of 1981, have always had problems with the Black Hawks and they fell into an irreparable situation by dropping the first two games at home. A crowd of 20,960 in Chicago on Saturday saw Minnesota win one, but the Hawks wrapped it up Sunday, 5-2.

A year ago, a Minnesota club that finished ninth overall had moved into Boston, where it had not won in 35 regular-season games, and whipped the Bruins twice en route to a first-round sweep.

St. Louis' elimination of Winnipeg, a .500 team, produced a situation in which, should Edmonton bow out, the Campbell Conference would be represented in the final by a sub-.500 club. Vancouver earlier wiped out Calgary in three straight, the only sweep of the round.

The New York Rangers, after dropping the first game to Philadelphia, took three in a row to advance to the Patrick Division final.

All divisional championship series begin Thursday on the ice of the club with the best regular-season record. In the case of the Norris Division, St. Louis earns the host role over Chicago on the basis of more regular-season victories, as each collected only 72 points.

Los Angeles, lest any Washington fan question the difficulties created by realignment, finished two points behind the Capitals, despite Washington's more difficult schedule.