HAMILTON, ONTARIO, SEPT. 12 -- Nobody comes back from a three-goal deficit against the Soviet Union's powerful hockey team. It has been the Soviets' custom for years to take advantage of a pressing opponent's mistakes to build the score ever higher.

Friday night in Montreal, though, Canada was behind, 4-1, with only 21 minutes left and scored the next four goals of the game. Although a freak carom enabled the Soviets to tie it and they went on to win, 6-5, in overtime, the comeback gave Canada a confidence boost for Sunday's second game of the best-of-three Canada Cup final.

Canada, missing injured wingers Claude Lemieux and Kevin Dineen and with Rick Tocchet skating on a limited basis, was playing with three lines against the Soviets' four. The visitors are reputed to be the best conditioned players in the world, so it was expected they would dominate the third period.

Instead, after Ray Bourque cut the lead to 4-2 with 42 seconds left in the second period, the Soviets appeared to panic, abandoning their usual pinpoint patterns for helter-skelter play that often broke down.

The Soviets were getting plenty of shots, 16 in the third period. Meanwhile, Canada was firing 13 on goalie Sergei Mylnikov, who frequently seemed bewildered by the defensive shortcomings in front of him.

"They put a lot of pressure on us in the first period and a half," said Washington Capitals winger Mike Gartner, who was voted Canada's best player. "But when the game is close or they're trying to come from behind, they seem to play a different hockey game.

"They give the puck away and try to press a lot. I think they felt the heat a lot when we started to come back. That had to be a great hockey game to watch. It's not very often you get to see a team come from three goals down against the Soviets.

"We've always felt confident we can beat the Soviets. We still felt that way when we were three goals behind. And just because we're a game down doesn't mean we're giving up on the series. We expect to win it."

If there was a dark side to Canada's performance, other than the final score, it was the power play, which clicked only once in eight chances and yielded a shorthanded goal. Twice Canada received two-man advantages; the first lasted 43 seconds without a shot on goal, the second ended in 10 seconds with a foolish penalty by Bourque.

In previous tournament games, Canada had converted seven of 24 extra-man chances, featuring a unit of Wayne Gretzky, Mario Lemieux, Mark Messier, Paul Coffey and Bourque. But the Soviet penalty killers were superb and repeatedly took advantage of a moment's hesitation to dump the puck down the ice.

"They were very aggressive killing penalties," said Washington's Larry Murphy, a second-unit point man. "That's the way they've always played. European teams go after you and they're certainly the best of the European teams."

Whether the Soviets are the best in the world will be determined no later than Tuesday, when the "if necessary" third game is scheduled here. Win or lose, Canadian hockey fans can only hope the rest of the series matches the opener in excitement and intensity.