Trainer Gai Waterhouse has taken positives from her colt Pierro's recent shock loss ahead of Saturday's $3 million Cox Plate (2040m) at Moonee Valley on Saturday.

The short-priced favourite for the Group One Caulfield Guineas (1600m), Pierro was run down near the line by All Too Hard, suffering his first loss in nine starts.

The consensus at the time was that the colt had to work too hard early in the race and weakened nearing the finish.

But Waterhouse agreed with Pierro's owner, Greg Kolivos, that the run was likely to have improved Pierro for the longer trip.

"It could well do," Waterhouse said.

"It might have because he looks magnificent, he really does look fantastic and he's a ball of muscle."

Waterhouse has modified Pierro's work in the lead-up to the race in which she has two other runners - a second three-year-old, Proisir, and outstanding mare More Joyous.

"His work is slightly different now. It's more dour," she said of Pierro.

"The other colt, Proisir, is a little bit more sharp, a little bit more on the toe.

"Some people say going to the Cox Plate, the dour type might be better....But both colts are very much on target."

The three all worked well at Flemington on Wednesday morning.

Waterhouse settled on Pierro when asked which of the trio she considered her best chance.

"It's hard but I've always been a great admirer of Pierro. I can't see why he can't win this race and I've set him for it all along.

"But, as I say that, Proisir has taken quantum leaps since he's come to Victoria - and the mare (More Joyous) is just spot on."

Waterhouse decided against taking her runners to Moonee Valley to work at Tuesday's Breakfast with the Best to avoid any extra excitement.

"Especially having two colts, they think it's race day and I don't want them wasting any excess energy, except at the races," she said.

"It's a small track with a lot of people, a lot of noise and those horses are really going to be sort of hyped-up on the afternoon."

Waterhouse was less than impressed by the decision to stage the Manikato Stakes meeting on Friday night, the eve of the Cox Plate.

"I wouldn't if I was running the club, but I'm not running Moonee Valley," she said.

"They're doing a very good job but I think it's a shame that they've chewed the track up before their premier meeting of the year, the Cox Plate."