"Every day he's been here he's improved. He's loving the work, he's doing it well and he's very happy.
"But I think you saw another aspect of him today."
Tres Blue galloped over 1400m at Werribee with race jockey Tommy Berry in the saddle, finishing off strongly and continuing his work well after the line.
"He picked up nicely and finished it off more like a sprinter than a stayer," Waterhouse said.
The gallop is likely to be Tres Blue's final fast work before Tuesday's race for which he is a $21 chance.
But his workload won't decrease for at least a few more days.
"He's put on an enormous amount of weight since he's been here - he's strengthened right up," his trainer said.
"In 10 days he's put on 25kg; he's just thriving.
"The more work he does the more he eats. He's loving it.
As unlikely as it may be that any doubt existed in the Waterhouse mind over Tres Blue, there was just a little to do with the horse's relative inexperience.
However, such thoughts have since been expelled.
"I think he's well and truly mature enough," she said.
"No problems with maturity."
As impressed as she was with her own horse, Waterhouse also allowed her attention to be diverted to the English galloper Brown Panther who she said was the second-best worker of the morning behind her horse.
"That brown horse worked very, very well," she said.
"There's a tip-and-a-half."
Brown Panther, whose owners include former England soccer star Michael Owen, is also a $21 Melbourne Cup chance.
Meanwhile, Complacent has lost his place at the top of Victoria Derby betting after coming up with one of the widest gates for the classic.
The pre-post favourite before the draw, Complacent has barrier 16 in the full field of 16, plus two reserves. His stablemates San Diego and Tupac Amaroo fared better with barriers six and eight, respectively.
Complacent has eased from $4 to $4.80 with TAB fixed odds, which has installed Savvy Nature as the new favourite, although his price also drifted after he, too, drew awkwardly.
The Vase winner heads betting at $4.60 from gate 13 while Polanski remains third pick at $8 after drawing the rails.
Criterion, runner-up in the Spring Champion Stakes, will make his Victorian debut in the race and will do so from barrier 14, while Drago has drawn the outside.
- AAP