Success in country meetings has convinced Sue Grills that Under The Thumb warrants a trip from Tamworth for a Highway Handicap debut at Randwick.

While stablemate Fickle Folly will stay at home after she was pulled from two races on Saturday's card, the four-year-old gelding has been challenged to make the step up to city racing.

"He deserves a chance down there. He's won three races and if we don't go now, you miss out," trainer Grills said.

"If he wins another race he's not eligible for them (Highways) then."

Under The Thumb opened this preparation in March with victory on his home track in a class two handicap and then finished runner-up in a benchmark 63 at Quirindi on May 8.

"This will be the hardest race he's been in for sure," said Grills, who rated Under The Thumb among the frontrunners of her 28 horses in work.

Christian Reith has been booked to ride Under The Thumb for the first time and is reasonably weighted with 55kg for the 1100m race.

Fickle Folly, meanwhile, stays in Tamworth after being nominated for the At Sea Handicap (1100m) and the Highway.

"She was weighted out of one race and the other one is too tough, so I'll wait to a more suitable race comes along," Grills said.

The three-year-old filly could be in Sydney for a benchmark fillies and mares race at the next Randwick meeting on June 10.

Grills was confident Fickle Folly, who last raced in the Listed Denise's Joy Classic (1100m) at Scone on May 13, would acquit herself well when called upon.

"She's had three weeks off, she's really well," she said.

Fickle Folly started her well-spaced preparation in October and has three wins from eights starts.