ALL the leading contenders for this year’s World Cup have a chance to gain a psychological edge over their rivals in three fascinating clashes between the northern and southern hemisphere nations on Saturday. In the most intensive day of top-class international rugby before the World Cup in October and November, world champions South Africa play the improving Wales in Cardiff, Australia meet England in Sydney and New Zealand take on France in Wellington. The prestigious Tri-Nations tournament involving the Springboks, All Blacks and Wallabies in July and August will show who rules the dominant southern hemisphere in the run-up to the World Cup.