TORONTO (AP) _ The New York Yankees can expect a chilly reception from the weatherman as well as the fans for tonight's opening game of a crucial three-game American League East showdown series with the Toronto Blue Jays.

Jim Davis of the Toronto office of Environment Canada said a cold front moving east from the Dakotas will bring showers, clouds and winds to the Toronto area while dropping weekend high temperatures into the mid to upper 50s.

''It doesn't look too promising for the weekend,'' Davis said.

He added that the possibility of winds off Lake Ontario could add to the discomfort of the players and fans in the lakefront stadium.

Davis said that moderate weather was expected next week, when the Blue Jays, if they win the AL East title, would host the first two games of the AL playoffs.

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MONTREAL (AP) - Montreal Expos President John McHale said it is too early to tell whether the National League baseball club will equal last year's losses of about $3 million.

''I guess it (a loss) is obvious, when you draw fewer people and operate on the same basis as before,'' McHale said.

Although the Expos unloaded Gary Carter and his seven-year, $15-million contract in the off-season, the club still has one of the largest payrolls in the game.

''There's really only one reason why we have trouble competing with other clubs,'' McHale said. ''That's the dollar differential (between Canada and the United States). We've been saying that a long time. We're fortunate here to have ownership that is dedicated to the game and to keeping it sound. Budget has never affected our ability to put a team on the field.''

According to the players' union analysis of the owners' books, the Expos were one of the seven biggest money-losers in baseball in 1984. McHale said the team has taken several steps to tighten up operations, such as guaranteeing contracts for no more than three years.

''One of the sobering facts about our game is that there is $50 million being paid right now to players who are no longer in major-league baseball,'' he said. ''Most of that is in long-term, guaranteed contracts.''

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HAMILTON, New Zealand - Australia's Edwina Kennedy shared the lead with local player Joanne Green after the first round of stroke-play at the New Zealand Amateur women's golf championships here Friday.

The pair shot 4-over-par rounds of 76 on another disappointing day of scoring on the immaculate St. Andrews course, beating New Zealand representatives Debbie Smith and Jan Cooke by one stroke.

Kennedy, who won the New Zealand foursomes title yesterday with compatriot Louise Briers, took a share of the lead thanks to a 1-over-par tour of the back nine.

''I feel I hit the ball a lot better today after a bad start but I just want to get a few putts in tomorrow and then I'll feel better,'' she said.

Briers failed to break 80, while Australian junior champion Louise Mullard also found the finishing holes tough in carding an 83.

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JAKARTA, Indonesia (AP) - Indonesian challenger Yani ''Hagler'' Dokolamo said Friday that he is fully confident that he will beat International Boxing Federation junior flyweight title-holder Dodie ''Boy'' Penalosa of the Philippines when they meet in a title bout in Jakarta on Oct. 12.

''I am combat-ready and just now I am in my prime condition,'' the 18-year- old challenger, who started his professional boxing career five years ago, told reporters at his training camp.

Yani - who always has his head shorn clean to resemble his idol, Marvelous Marvin Hagler, the undisputed lightweight champion - refused to predict whether he would knock out Penalosa or defeat him on points.

The 15-round match will be Penalosa's third defense of his title, which he won on a 12th-round knockout over former champion Satushi Shingaki of Japan in December, 1983.

Penalosa knocked out South Korean challenger Kim Jae Hung in Seoul last year and defeated another Korean challenger, Choi Chum Hwan, on points in the Philippines last November.

Penalosa will earn $80,000 from the fight and Dokolamo will get $40,000, the largest ever offered to an Indonesian boxing challenger.