While the pacer is the class horse of the field in tomorrow’s 2400m feature, he is going to need to bring all of his best qualities to overcome a massive 40m back mark.
Williamson knows exactly how big that task could be, especially if Sand Wave’s key rivals set a fast tempo from their lesser handicaps.
But the trainer-driver is comfortable in knowing he has his horse ready to run the best race he can, no matter what circumstances are thrown up in front of him.
"It certainly won't be easy off 40m," Williamson said.
"I suppose the small field does help, but it'll just be what happens in front of him.
"But he's well, and he'll go a good race."
Mr Cash Man starts from a 10m handicap in the Wario Cup for Williamson.
The pacer had a temporary stable movement lodged as he is based with Tyler Dewe in the hope the horse can bounce back to the kind of form that enabled him to win the South Of The Waitaki event during New Zealand Cup week.
"We just went for a bit of a change of scenery. He raced at Ascot Park last start and I just decided afterwards why don't we leave him here for a change of scenery and try something new."
"If he does bring his best form, he wouldn’t be without a chance."
The unbeaten Miraculous starts in the Southern Supremacy Stakes heat for the Williamson barn.
The pacer looks the horse to beat, while stablemate Ultimate Weapon looks a trifecta and first4 player.
"Miraculous is a classy horse. He's got nice point-to-point speed, and he's pretty tractable.
"The other fella is probably not the finished product yet and he is a good staying horse.
"I think over the longer trips later on will suit him better.
"But you'd have to lean towards Miraculous."
Another Williamson pairing go head to head in the Southern Oaks heat in Flying Ellie and Ruby Roe.
"There isn't much between them, and it probably comes down to the run, who will finish in front of the other.
"But they both seem very well.
"I'd say the Flying Ellie might be a little bit more forward this week.
"But I'm in saying that Ruby Roe trialled lovely as well, and I've been happy with their both of their work.
"So, there’s not much between them."
Another Williamson pairing clash is in race 11 between Itoje and Micaitlen Denario.
Itoje has the benefit of recent racing, while Micaitlen Denario comes in fresh from barrier 1.
"Micaitlen Denario has got a nice draw and shouldn't have to do a lot of work from there.
"So that brings her into calculations.
"But Itoje is a very smart horse, and I think he's ready to show his best on Sunday."
Zamperini returns to Winton tomorrow after impressing in his debut fifth.
The pacer gets a big draw upgrade from his first run, moving from barrier 8 to barrier 3.
"He's got a couple of wee fancy steps in him, but he's quite a strong horse.
"He always runs on, so I think in that type of field, if he didn't settle too far away he should be there or thereabouts."
Rakapmurph rounds out the outstanding Williamson lineup when starting in race 12.
The pacer disappointed in his last start at Omakau, but he has produced a handy workout effort since being freshened.