The trainers and connections of three Sydney Cup contenders have an added incentive for their runners to claim the $2 million Group One staying feature at Randwick.

For the first time the Australian Turf Club has offered a bonus as part of a strategy to boost the field size.

The ATC will pay $100,000 to the owners and $50,000 bonus to the trainer if Five To Midnight, Ormito or Peribsen win or run a place in Saturday's 3200m race.

Those horses qualified for the bonus by winning or being placed in a series of lead-up races.

The Lisa Latta-trained Five To Midnight was second in the Group One Auckland Cup last month, the Darren Weir-trained Ormito was runner-up in the Adelaide Cup while French stayer Peribsen was third in the Manion Cup for John O'Shea.

Adelaide Cup winner Fanatic was also eligible but Lindsay Park had to scratch the mare on Tuesday because of injury.

ATC joint acting chief executive James Heddo said the bonus had helped boost the field to 20 runners, after 14 entered last year.

'This is the first time in many years the Sydney Cup has attracted a capacity field," Heddo said.

"We will continue to look at how we may be able to extend the bonus to encourage more owners and trainers to aim at Sydney's iconic two mile race.''

The TAB had Peribsen at $21, Ormito $26 and Five To Midnight $51 after Tuesday's barrier draw,.

Almandin, the 2016 Melbourne Cup winner, led the market at $4.