Having confirmed himself as a staying star in the spring handicaps, Melbourne Cup winner Vow And Declare gets an opportunity to become a weight-for-age force.

Vow And Declare makes his weight-for-age debut in Saturday's Group One Australian Cup (2000m) at Flemington, his first start since winning the Melbourne Cup (3200m) in November, and trainer Danny O'Brien says the four-year-old is in superb shape.

"He's about 30 kilos heavier than when he raced in the Melbourne Cup and we're hoping that makes him just that little bit bigger and stronger, and hopefully he's got a little bit more speed for a 2000-metre race," O'Brien said.

O'Brien believes 2400m to 3200m are Vow And Declare's best distances, but if successful on Saturday the stayer would join a select list of horses to have won the Melbourne Cup and Australian Cup in the same season.

Since the Australian Cup became a 2000m weight-for-age race, Let's Elope, Makybe Diva and Fiorente have claimed the double in the the same season.

Along with the Melbourne Cup, Vow And Declare's spring campaign last year included a fourth in the Turnbull Stakes (2000m) and second in the Caulfield Cup (2400m).

"We're looking forward to seeing what else he might be able to do now for the rest of the season as a four-year-old and obviously the first step is that Australian Cup," O'Brien said.

"I'm sure he will run really well.

"We'll leave the form analysts to decide how he measures up, but his Caulfield Cup and Melbourne Cup form is really good form and he'll enjoy the cut out of the ground.

"He loves Flemington and loves 2000 metres, he was very competitive in the Turnbull Stakes so I'm sure he's a live chance."

The $4 million Queen Elizabeth Stakes (2000m) next month in Sydney and the Doomben Cup (2000m), The Q22 (2200m) and the Tatt's Cup (2400m) in Brisbane are Vow And Declare's targets ahead of his Melbourne Cup defence.

Vow And Declare won the Tatt's Cup last year when it was run over 3000m on his path to the big spring handicaps.

"It's a good campaign for him," O'Brien said.

"It just enables us to keep him ticking over throughout the winter and bring him back here nice and fit and strong and not have to race him too many times in the spring, so that hopefully he can get to Melbourne Cup day again in 2020 in the best possible shape to run another great race."

Vow And Declare was at $12 for the Australian Cup on race eve while O'Brien will also run Venice Beach who is at $151.