Melbourne Cup outsider Future Score has been ruled out of the $8 million race after failing a veterinary test.
One of two runners inspected on race morning, Future Score was withdrawn because of lameness.
Future Score's defection leaves a field of 23 to face the starter in the famous race after Delphi was passed fit.
Delphi, who has met with betting support at longer odds, was lame on Cup eve but satisfied Racing Victoria veterinarians of his soundness before Tuesday's scratching deadline.
The import will be trying to rebound after a Caulfield Cup disappointment and will be ridden by champion jockey Damien Oliver.
Oliver is chasing his fourth Melbourne Cup win.
Twenty-two Cup horses were cleared to race on Monday, including the UK stayer Spanish Mission.
Spanish Mission attracted additional veterinary scrutiny last week before given the all-clear to race ahead of an acceptance deadline on Saturday.