SYDNEY (AFP) - World champion Mollie O'Callaghan was untouchable in the 100-metre freestyle and Emma McKeon too hot over the 100m butterfly, but it was not enough to prevent the United States edging out Australia to claim another "Duel in the Pool" crown on Sunday (Aug 21).

Teenager O'Callaghan burst on to the scene this year, taking both the world and Commonwealth 100m titles among a flurry of medals, and she comfortably won again at the Sydney Aquatic Centre.