John Sargent's potential Melbourne Cup hope is ready to roll in the Sydney Cup but he needs a confirmed starter to drop out before the field is finalised.

The Randwick trainer only brought Rock On across from New Zealand to get accustomed to racing in Australia via the Group Two Chairman's Handicap (2600m) on April 1, but now he could face an even tougher test on Saturday.

The four-year-old gelding is one of two horses not assured a start in the 14-horse field which reassembles after the original running of the Group One staying feature (3200m) was abandoned mid-race at Randwick on April 8 when Almoonqith broke down and Who Shot Thebarman's also fell.

Sargent is hopeful Rock On, third behind Sydney Cup favourite Big Duke in the Chairman's Handicap, will ultimately start.

A decision on whether Annus Mirabilis takes his place will be made after trainer Stuart Webb watches him gallop on Tuesday.

"There's one debating whether to pay up after a gallop. There may be others, fingers crossed," Sargent said.

Godolphin's English visitor Polarisation has to pass a veterinary inspection on Tuesday morning after the stable reported he had had heat in a fetlock over the weekend.

Polarisation crossed the line first in the original Sydney Cup with six riders unaware the race had been called off.

Rock On's connections stumped up the $11,000 entry fee without hesitation after he backed up well from his Australian debut on a heavy track.

"Now that he's got fresh legs we thought the race would suit him. He's acclimatised," Sargent said.

"This was a trip over to give him experience for Melbourne in the spring and he's done that well. Now there's a $2 million dollar race, you might as well try and run in it."

Sargent described Rock On as a "good lightweight chance" should he make the cut after he was given just 51.5kg, a 4kg reduction on what he carried in the Chairman's Handicap.

Rock On was listed at $26 on TAB fixed odds alongside Annus Mirabilis, Boom Time and Kinema.

The field is confirmed on Wednesday.