Jumpers Stand To Gain and Thubiaan will race at Ballarat on Sunday in a bid to keep alive their chances of sharing in a $300,000 bonus.

The Melbourne Racing Club is offering the incentive to the connections of any horse that can win three legs of a six-race series.

Stand To Gain and Thubiaan each won opening races in the series at Warrnambool earlier this month when Stand To Gain claimed the Galleywood Hurdle and Thubiaan the Brierly Steeplechase.

On Sunday, Stand To Gain lines-up in the Australian Hurdle (3400m) with Thubiaan to tackle the bigger jumps in the Australian Steeplechase, also over 3400m.

The Grand National Hurdle at Warrnambool on July 12 and the Grand National Steeplechase at Ballarat on July 26 comprise the remaining legs of the series.

A winner of the 2011 Sydney Cup when prepared by Chris Waller, Stand To Gain has been in the care of Bob Challis for more than two years and finished third behind Gotta Take Care and Fieldmaster in last year's Australian Hurdle at Sandown.

Challis's partner Liz Irwin said Stand To Gain had come through his win in the Galleywood in excellent order and confirmed Paul Hamblin had retained the mount.

Irwin said the only hiccup in Stand To Gain's program had been a change of track rider after Irwin was injured in a recent fall.

"He's a much happier horse this time in and his whole preparation has been a lot better," Irwin said.

"He's had a slight change in track riders but we're hoping that doesn't make too much of a difference to him on Sunday."