The Melbourne Cup may be his grand final, but jockey Glen Boss says Puissance De Lune is primed to score a breakthrough Group One win in Saturday's Underwood Stakes at Caulfield.

Boss and trainer Darren Weir are conscious of the need for Puissance De Lune to win at Group One level to maintain his status as the country's No.1 stayer.

But they are also conscious of the the task ahead of the horse thanks to the presence in the Underwood of the unbeaten Atlantic Jewel and Foreteller who beat Puissance de Lune home by a nose the Makybe Diva Stakes.

Boss has been on board Puissance de Lune for his past five races which have netted four wins and the second placing in the Makybe Diva last Saturday week.

He says the six-year-old has run above his expectations in his past two outings.

"His grand final is weeks away but I'm expecting him to run well," Boss said.

"It is shaping as the foremost race of the carnival. To get these great horses in the carnival all coming together for this race - it's about the time they all stand up to be counted."

The Mark Kavanagh stable declared Atlantic Jewel a definite Underwood starter on Tuesday, days after her easy win in the Stocks Stakes at Moonee Valley.

Also among the 26 nominations in the class field are last year's Melbourne Cup winner Green Moon, Australian Derby winner It's A Dundeel, Queensland Derby winner Hawkspur, Victorian Oaks winner Dear Demi and Australian Cup winner Manighar.

"This is a highly anticipated race that basically shapes the Caulfield Cup, the Cox Plate and the Melbourne Cup," Boss said.

In the Melbourne Cup weights announced on Tuesday Puissance de Lune was given 54.5kg, a little more than Boss had anticipated.

"I was hoping for 53.5kg but I've got to cop that and hope he lives up to his expectations," Boss said.

Boss won three consecutive Cups on Makybe Diva from 2003-2005.