Sir Delius, a leading contender expected to achieve the prestigious Cox Plate-Melbourne Cup double, has been withdrawn from both races after veterinary scans revealed a heightened risk of injury. Following a compulsory CT scan and a subsequent PET scan at the University of Melbourne Equine Centre, an independent panel of specialists advised Racing Victoria stewards that Sir Delius should not compete in the 2025 spring racing carnival to avoid potential injury. Co-trainers Gai Waterhouse and Adrian Bott accepted the decision, which ended their plans to use the Cox Plate as a lead-up to the Melbourne Cup.

With Sir Delius out, Via Sistina has become the new Cox Plate favorite, while Irish-trained Al Riffa leads the betting for the Melbourne Cup. Sir Delius had been a strong favorite after impressive wins in the Turnbull and Underwood Stakes, and his withdrawal has led bookmakers to offer refunds on bets placed for him in both races. This development marks a significant shift in the spring racing landscape, impacting key betting markets and the strategies of top trainers.