Gai Waterhouse has set her sights on a second Melbourne Cup after The Offer swept to an effortless Sydney Cup win.

The Offer gave Waterhouse her second Group One victory on Saturday after Diamond Drille scored a surprise Queen Of The Turf Stakes win.

Both horses were partnered by Tommy Berry who showed composure beyond his 23 years to ride a patient race on $3.30 favourite The Offer just a couple of weeks after the sudden death of his twin brother Nathan.

"The hardest thing is coming back here and he's the first one to give me a cuddle but he's not here to do that any more," Berry said.

"But I'm glad I've come back to ride and I'm making him proud."

The Offer had won his past two starts on heavy tracks but with Randwick drying out during the day he was a betting ring drifter.

Berry settled him worse than midfield but was able to get to the outside when the field straightened and The Offer let loose with a blistering run to sweep to a 3-3/4 length victory.

Opinion saved ground towards the inside for second with Sertorius another 1-1/2 lengths away third.

Waterhouse won her first Melbourne Cup last spring with Fiorente and said The Offer would be set for Australia's most famous race.

"I've got the Melbourne Cup there on the table today and I'll put the Sydney Cup next to it," Waterhouse said.

"What a stayer. Look at the rest of them, he's donkey-licked them.

"Look out Melbourne Cup 2014."

Bookmakers reacted quickly to the win and The Offer is now a $15 favourite for the Melbourne Cup.

Jason Collett said Opinion was game but couldn't match the winner.

"It was a much-improved performance but it's a long straight," Collett said.

Sertorius' jockey Ryan Maloney was proud of his horse's effort over the 3200-metre trip.

"His run was enormous for his first go at two miles," he said.