Charlie Simmer and Dan Bonar scored two goals each and goalie Mario Lessard turned back 40 shots last night, leading the visiting Los Angeles Kings to a 7-4 triumph over the Edmonton Oilers and a stunning upset in their Smythe Division best-of-five semifinal series.

The Kings, 17th in the overall league standings entering the playoffs, advance to the division final against the Canucks starting Thursday night in Vancouver.

The Kings, taking advantage of tentative checking, led, 6-2, after 40 minutes.

Simmer, playing with Doug Smith at center, staked the Kings to a 2-0 first-period lead when he scored twice on rebounds.

Wayne Gretzky cut the lead to 2-1 with a tip-in at 7:59 on a power play. But Los Angeles rookie Daryl Evans, in the minors for all but 14 of the Kings' games this year, made it 3-1 when he intercepted a clearing pass by Jari Kurri and scored his fourth playoff goal.

Islanders 4, Penguins 3: John Tonelli took a lesson from Bob Nystrom on how to score in overtime.

Nystrom, who won the Stanley Cup for the Islanders in 1980 with an overtime goal against Philadelphia, assisted Tonelli on the goal that ended a dramatic comeback that gave New York the victory over the visiting Pittsburgh Penguins in the fifth and deciding game of their first-round playoff series.

"Bobby should know how to do it, right?" asked Tonelli after his goal 6:19 into the extra period. "I just thank God I was in the right place at the right time."

The Islanders advance to the Patrick Division best-of-seven final series against the New York Rangers, beginning Thursday night at Nassau Coliseum.

Pittsburgh coach Eddie Johnston said his team had its chances.

"We came out in overtime aggressively and had three or four good opportunities to score," Johnston said. "But our plan didn't work."

New York came back from a two-goal deficit late in the third period to tie at 3 with 5 1/2 minutes to go. The victory extended the Islanders' home unbeaten streak to 26 games.

The Penguins, who finished 43 points behind the first-place Islanders in the Patrick Division, seemed to be out of contention in the best-of-five series after losing the first two games, 8-1 and 7-2. But they rallied with a 2-1 overtime win and a 5-2 victory last weekend.

Penguin goalie Michel Dion was the star of the deciding game--he had 42 saves--until the Islanders rallied, spoiling Pittsburgh's hope of becoming the first team ever to win a best-of-five playoff series after losing the first two games.

"Everyone spilled their hearts out there," Dion said. "We gave it all we had."