Barriers can win or lose a race and Craig Williams is hoping they won't be the determining factor for his mounts in two stakes races at Moonee Valley.

First starter Boston Light has drawn the inside barrier in the McKenzie Stakes (1200m) while Gregers has drawn 11 in a field of 13 in the Carlyon Stakes (1000m) on Saturday.

Williams believes Gregers is well suited by the conditions of the Carlyon Stakes and said the mare goes into the race in perfect shape.

Having trialled the daughter of Commands in preparation for her first-up run, Williams said she won't be lacking in fitness.

"I would rather have drawn a single figure but I'm on a really nice horse," Williams said.

"She's got very good stats at the Valley and has good first-up form.

"Even though she's topweight, I believe she's very well off under the conditions of the race."

Gregers holds favouritism at $2.10 for her return.

While Williams will have to navigate a wide draw on Gregers, he's hoping the inside alley on Boston Light will not be a disadvantage at the colt's first outing.

Williams has ridden the son of Fastnet Rock in a jump-out at Flemington and again in a track gallop at Moonee Valley and is of the opinion the three-year-old has plenty of ability.

He said while he handled the tricky Moonee Valley circuit in a familiarisation gallop, it would be different under race conditions.

"It will be interesting to see how he goes at his first start and from barrier one, whether it becomes an advantage or a disadvantage," Williams said.

"He's got a lot of scope and he feels like he's got very nice talent so it's a nice starting point for him to see where he figures in the spring."

Boston Light is a $7.50 chance in which Greco is the $4.60 favourite over NSW visitor Odyssey Moon at $4.80.