On his 23rd birthday, Steve Smith of the Edmonton Oilers committed one of the biggest blunders in the history of the Stanley Cup playoffs.

Smith, a rookie defenseman, put the puck into his own net off goalie Grant Fuhr at 5:14 of the third period tonight, allowing the Calgary Flames to end Edmonton's two-year Stanley Cup reign with a 3-2 victory over the Oilers.

"It was a human error and I quess I'll have to live with it." Smith said with tears in his eyes. "We worked so hard and deserved better."

Stationed behind his net and unpressured, Smith attempted to pass diagonally across the crease. The puck hit the back of Fuhr's left ankle and caromed into the goal behind him to break a 2-2 tie. The goal was credited to Perry Berezan and sent the Flames to the Stanley Cup semifinals against the St. Louis Blues Story, D2 .

Calgary center John Tonelli insisted the winning goal was not lucky.

"Lanny McDonald forced him to shoot the puck," Tonelli said.

The play marked a shocking end to a seven-game Smythe Division upset in which the Flames won three of the four games played at Edmonton.

The heavily favored Oilers had won the Cup two straight years and had dreams of a dynasty. The Oilers wrested the Cup from the New York Islanders, who captured it four consecutive seasons.

The winner was not the Flames' only odd goal. Their second goal came on a drive from the blue line.

"It's unfortunate they got that goal on a shot from the blue line and one from behind the net," Edmonton star Wayne Gretzky said. "That's going to happen in a hockey game."

Berezan received credit for the goal because he was the last Flame to touch the puck before Smith mishandled it. It was his first goal of the playoffs and he was on his way off the ice when it was scored.

After the fluke goal, the Oilers rallied frantically and pulled their goalie with a minute to play but could not beat goalie Mike Vernon. The Oilers received one final chance to score with 35 seconds left when the Flames were penalized for having too many men on the ice. With Fuhr out of the net, the Oilers had a six-on-four skating advantage, but could not score.