Over a long period of time, jockey Craig Williams has had considerable success in the Royal Blue, Lime Hoops, Hooped Cap of owners Colin and Janice McKenna.

Williams will partner a couple of the husband-and-wife part-owned gallopers in two feature races at Caulfield on Saturday, firstly Modown in the Group 2 Sandown Guineas (1600m) then 40 minutes later Shock 'Em Ova in the Group 2 Zipping Classic (2400m).

Modown will be having his fourth start in the Guineas with Williams being aboard the three-year-old in his three starts to date.

The jockey headed to Caulfield on Tuesday morning to partner the Charlotte Littlefield-trained Modown in a gallop ahead of Saturday's contest.

"I was really happy with the way his attitude was, the way he worked, and I felt he showed a bit of maturity from his third-up run through to his piece of work on Tuesday," Williams said.

"He's a lovely horse, going the right way and I'm really looking forward to a solid performance."

Modown has been a work in progress, and the same can be said for Shock 'Em Over.

The five-year-old will be racing for only the tenth time on Saturday, having registered four wins and four placings and almost $330,000 in prize money.

Williams has been aboard Shock 'Em Ova in four of his past five starts, registering two wins at Caulfield.

"I've always had an opinion of the horse," Williams said.

"He's got a really good profile, he's been really well managed by Alex Rae and brought along slowly.

"He's not a straight-forward horse and the time Alex has taken with him is bringing out the best in him.

"I still don't think we have seen the best of him, but his attitude is improving, his manners are improving and he's displaying nice ability."

Under Saturday's weight-for-age conditions, Shock 'Em Over is not well-weighted, but Williams said Rae was looking to the future with the stayer.

As an 86-rated galloper, Shock 'Em Ova carries the same weight as 2019 Melbourne Cup winner Vow And Declare, a 106-handicap rated horse.

"Alex's opinion of the horse and where he wants him to be, then he needs to get that ratings boost so he's not running him to get a start (in the future), but he's running him in races where he wants to run him," Williams said.

"He's a patient trainer and the horse will decide where he ends up, but Alex has got some nice long-range plans for the horse."

Williams said the McKenna's, who have a large investment in both racing and breeding, should be applauded for giving up-and-coming trainers like Rae and Littlefield, the opportunity with promising horses.