Champion jockey Glen Boss knows what it takes to win Australia's major staying races.

The Singapore-based three-time Melbourne Cup winner will fly through the night to make Saturday's re-run of the Sydney Cup at Randwick.

Boss is chasing his second Sydney Cup win and says being aboard the favourite Big Duke on a track rated in the heavy range on Friday will give him a "massive" advantage.

He won his three Melbourne Cups and the Sydney Cup on champion mare Makybe Diva and believes Big Duke has the attributes to win.

"It's hard to find a point where this horse can't win. He's obviously effective on soft ground, he's effective on heavy ground," Boss told RSN927 radio on Friday.

"He can get on the bridle a bit this horse and Craig (Williams) has done a terrific job with him to make him relax.

"If you look at him in the Sydney Cup, he looks completely in the zone the whole way before the race gets called off."

Boss said Who Shot Thebarman, who lost his rider in the aborted April 8 Cup program, was the horse to beat in the re-run.

"But he's got to give me five kilos which might be a fair bit to give over two miles," he said.

Boss replaces Williams, who this week failed to get a careless riding ban reduced on appeal.