OMAEZAKI, Japan (AP) _ Britt Dunkerbeck of Spain, the 1989 women's overall World Cup champion, won two women's course races Sunday and her brother, Bjoern, the 1988-89 champion, captured one men's race in a $150,000 wind surfing competition.

American Robby Naish placed second, followed by Robert Teriitehau of France, in the men's second course race at Shiraha Beach in Omaezaki, 108 miles southwest of Tokyo.

Australian Bruce Wylie won the men's first course race, followed by Thorkil Kristensen of Denmark and Sweden's Anders Bringdal.

In the second women's course race, Natalie Simon of France placed second and Rhonda Smith-Sanchez of the United States was third.

The Omaezaki meet, officially called the ''Sometime World Cup 90,'' is the second of the three Grand Slam events. The third competition is scheduled in Hawaii from Oct. 31-Nov. 9.

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AUCKLAND, New Zealand (AP) - Auckland beat New South Wales 55-13 Sunday to take an unbeatable lead in the six-team South Pacific Championship rugby union tournament.

The New Zealand provincial team retained its South Pacific title after scoring nine tries to two in a one-sided match at Eden Park.

Center Joe Stanley and fullback Matthew Ridge each scored a brace of tries for Auckland, while fly half Grant Fox kicked eight conversions and a penalty, missing only one of his 10 kicks at goal for a personal tally of 19 points.

The South Pacific Championship is contested annually by teams from Australia, New Zealand and Fiji.

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MADRID, Spain (AP) - Jose Cesar Souza of Brazil won the Madrid Marathon on Sunday, beating Spanish champion Vicente Anton and Ian Haggan of Britain.

The 27-year-old Brazilian completed the cource in 2 hours, 14 minutes and 24 seconds. Anton was second in 2:14:51, followed by Haggan, third in 2:16:55.