Chris Waller hopes the step back in distance won't count against Scream Park who is being prepared for a trip to Ellerslie for the inaugural Karaka Million 3YO Classic.

The colt has won two of his past three starts and an accomplished performance at Randwick on Saturday in a 1400m-benchmark race will stamp his passport for Auckland.

Sydney's leading trainer has been cautiously impressed with Scream Park in his second campaign but wants to see a compelling effort when he backs up from a 1600m-win in a three-horse field at Warwick Farm on December 23.

"He sat outside the leader and did everything right, I just don't know how strong the opposition was," Waller said.

"He'll get a true test here and coming back in distance is the big query."

Waller said he wanted Scream Park to be ridden more conservatively on Saturday, a task that falls to Hugh Bowman in his first ride since returning from a stint in Japan.

"We want to switch him off and get him to relax because he's likely to head to New Zealand for a million dollar race," Waller said.

The Karaka Million 3YO Classic (1600m) on January 27 is part of the race day preceding the premier yearling sale.

Among Waller's other Randwick runners is four-year-old Gretna, who races for the first time since September in a Benchmark 79 Handicap (1200m).

"We scratched her last week because we weren't happy with her blood count. Everything seems perfect with her now so I'm hoping she can race well first-up," Waller said.

Fortensky returns from a spell in the same race and will be trying to win first-up for the second successive preparation.