She then had wins in the Memsie (1,400 metres) and Feehan Stakes (1,600 metres), but was narrowly beaten by Fairway in the Turnbull Stakes (2,000 metres). A natural frontrunner, like Sunline, Fairway refused to hand up the lead to Sunline, who was forced to chase, and held her at bay down the straight. It was Sunline's third defeat over the distance from as many starts away from Moonee Valley, but it was a great improvement on her previous defeats, especially since Fairway was a multiple Group One winning three-year-old the previous season. Sunline fans regard her next run as one of her greatest. On the last Saturday of October, Sunline took control in the rain-affected going to win the Cox Plate by seven lengths from Caulfield Cup winner Diatribe, with Referral in third place. Perhaps unsuited in the conditions, fancied runners Tie the Knot (2nd in 1999), Sky Heights (3rd in 1999), and Shogun Lodge (conqueror of Sunline in the George Main Stakes) were beaten a combined margin of more than 100 lengths. In winning, Sunline became the first Australasian horse to pass $6 million in career earnings. Returning to New Zealand after the Cox Plate, the mare's owners revealed that Sunline had been part of a bidding war from five different countries, including the powerful Godolphin stables in the United Arab Emirates. All bids were rejected, and the mare was prepared for another trip to the rich, pre-Christmas international meeting in Hong Kong. In her final lead-up, Sunline raced away with the Auckland Breeders' Stakes at Pukekohe. In Hong Kong, she led all the way to win the International Mile (1,600 metres), narrowly holding off local icon Fairy King Prawn, with five lengths back to Adam, from Australia, in third place. While the victory in Hong Kong neither confirmed nor denied the oft-made claim of her fans that Sunline was world's best racemare, her Cox Plate victory saw the Australian and New Zealand Horse of the Year receive an invitation to compete in the world's richest raceday, the Dubai World Cup meeting in the United Arab Emirates. In early February, Sunline recorded her eighth win in New Zealand when she was too good for seven other Group One winners in the Waikato Sprint. The victory kept alive Sunline's wonderful record in her home country, which at career end would stand at 10 wins from as many starts.