A favourable report from Puccini's new jockey Craig Williams has gone some way to lifting Peter McKay's spirits ahead of the Australian Derby.

The New Zealand Derby winner's first Australian appearance in the Rosehill Guineas (2000m) was a disaster and posed more questions than answers for his trainer.

Jockey Michael Walker told McKay the colt had not handled the wet track and later said his saddle had slipped.

Not matter what, McKay was unhappy with the way Walker took Puccini to the front and into an early speed battle with Shamus Award with both finishing among the tail enders.

Williams galloped Puccini on the Randwick course proper on Saturday and said he handled the wet conditions well but McKay is still not convinced.

"I'm still not sure and hopefully we get some better weather this week," McKay said.

"I am going to ride him in the morning but we can't use the course proper. We have to use the Kensington track which is a dead five so that won't really tell me if he does handle the heavy.

"Craig said he did on Saturday so that's all I can go on."

McKay did take heart from NZ Derby runner-up Rising Romance's strong finishing performance for fourth in Saturday's Vinery Stud Stakes after the filly was checked mid-race.

One thing that has given the trainer a boost is the way Puccini has come through the Guineas.

"He has done really well and tightened up a bit," he said.

"I thought the Guineas might have taken something out of him but physically he is great."

Criterion's dominant performance to win the Guineas has him the $3.50 favourite to win the Derby (2400m) with the TAB keeping Puccini safe as the $6 second elect ahead of Guineas placegetters Thunder Fantasy and Teronado at $8.