Leading South Australian Derby contender Russian Camelot has been scratched from a lead-up race at Flemington but is still scheduled to head to the Classic in Adelaide.

Danny O'Brien withdrew Russian Camelot from Saturday's 1700m-Handicap on Friday afternoon, with the trainer saying on Twitter the colt had an inflamed throat.

O'Brien said Russian Camelot would head straight to the Group One South Australian Derby (2500m) at Morphettville on May 9.

A northern hemisphere bred three-year-old, Russian Camelot has two wins and a second from his four starts.

He had been odds-on favourite for Saturday's Flemington race having won a benchmark 1600m-race by seven lengths at Pakenham on April 9.

The colt ran at Pakenham after being scratched from a race at Caulfield five days earlier when he played up in the barriers.

The Lifeline, winner of the Caulfield race, has assumed favouritism on Saturday at $4.40 after Russian Camelot's scratching, ahead of the Chris Waller-trained filly Betcha Flying ($4.60)

"He's a good honest horse and he's very tough," The Lifeline's co-trainer Adrian Bott said.

"I think he can run out a strong 1700 metres, particularly at this point of his campaign.

"He can put himself right in the race and he's a genuine, tough horse that will be hard to run down."

The Group Three Chairman's Stakes, one of the key South Australian Derby lead-ups, is at Morphettville on Saturday with Dalasan favourite ahead of Victoria Derby winner Warning.