Richard Dunwoody will ride Mr Mulligan in the Sean Graham Chase at Ayr on Saturday, according to the jockey's agent Robert Parsons.
"It's not often that a Gold Cup winner comes up as a spare ride," said Parsons, yesterday.
The Cheltenham Gold Cup winner pleased trainer Noel Chance in his work morning.
"Mr Mulligan is good," stated the Lambourn handler. "He worked nicely with a couple of horses this morning. It was just a nice piece of work nothing too strenuous."
The nine-year-old, who won chasing's blue riband by nine lengths from Barton Bank, had made an encouraging reappearance when failing by two lengths to give 13lb to Gales Cavalier at Wincanton over an inadequate 21 furlongs last month.
"He had a nice pipe-opener at Wincanton," Chance added.