There is hardly a more encouraging phenomenon in racing than an enthusiastic Gai Waterhouse - and at Werribee on Wednesday she was at her passionate best.

The object of the Waterhouse ardour was her Melbourne Cup newcomer Tres Blue whose qualities have excited his trainer from the day he arrived from France.

But on Wednesday she discovered a new facet to a horse who is creeping steadily into Cup reckoning.

"He's very light on his feet," Waterhouse said.

"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 25 kilos, 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.

But 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.