It used to be "Chi-co." Now it's "Bill-ee." The New York Islanders' vocal fans aren't fickle, just responding to the latest whim of coach Al Arbour, who shuffled the cards at the start of the Stanley Cup playoffs and started Billy Smith in goal in place of reliable Chico Resch.

After nine playoff games, Smith has solidified his status, winning seven, including Thursday's 5-3 decision over the Montreal Canadiens when he stopped 35 Montreal shots.

The Islanders and Canadians resume their best-of-seven semifinal tonight at Nassau Coliseum, where the Islanders have dropped only one of their last 13 playoff games. The powerful Canadiens own a 2-1 lead, but not one of those "Bill-ee" boppers doubts that the local heroes will gain a tie.

"If we can get a couple of goals up on them, and put pressure on them, they'll fall apart just like anybody else," Smith said. "We should have come up with one of those two games in Montreal. They got the breaks there and we got the breaks here."

And, if neither team gets the breaks?

"Then we'll probably play all night and win up in a tie," Smith said.

In December, Smith was a cheerleader, watching Resch's magic act from the bench. In one 12-game stretch, Smith started two games and finished one. But, on Dec. 21, Smith shut out the Boston Bruins and afterward got enough work to finish with a 21-8-6 record and a 2.50 goals-against average. Still, Resch's 2.28 mark was the NHL's best outside Montreal and he was expected to bear the playoff burden. It hasn't worked that way.

"This is the biggest surprise to the hockey world," Smith said, "me playing instead of Chico. He had the better season, but at the end I had one hot game and Al went with me instead of Chico. I'm fourtunate to be in there."

In th past, Smith, an original 1972 expansion Islander, earned more cheers for his fighting than for his goaltending. When the big games came up, the paying spectators expected to see Resch. Now, they're satisfied with "Bill-ee." And the Canadiens, struggling with Yvan Cournoyer, Rejean Houle, Bill Nyrop and Pierre Bouchard on the injured list, are seeing red.

The other semifinal could end Sunday nigh in Boston, where the Bruins attempt to turn their 3-0 lead over the Philadelphia Flyers into a four-game sweep. Should they succeed, the Canadiens, for once, will be the team sweating while their next opponent enjoys a rest.