Leading trainer Ciaron Maher has capped off a stunning day by adding a Caulfield Cup win to his earlier triumph in The Everest.

Maher's charge Duke De Sessa — ridden by Harry Coffey — claimed victory in the $5 million Caulfield Cup late on Saturday afternoon.

The six-year-old gelding held off a late challenge from pre-race favourite Buckaroo in the 2,400-metre handicap.

Maher could not attend the Caulfield Cup as he was in Sydney to see seven-year-old mare Bella Nipotina win the $20 million The Everest at Randwick.

Ridden by Craig Williams and trained by Maher, Bella Nipotina went wide and finished strongly in the straight to win narrowly from 2022 winner Giga Kick in the world's richest race on turf.

Bella Nipotina is the first mare or filly to win the 1,200m race.

Growing Empire was third, with Lady Of Camelot fourth.

Maher, who also trains Growing Empire, was emotional after his first win in the race, before a packed crowd at Randwick.

"She's a beautiful horse to train," he told the Seven Network.

"She's been elite for the last five years and, yeah, it's unbelievable.

"To do it this late in her career, after 54 starts, it's unbelievable.

"We thought she was in career-best form and she got her conditions to suit."

Bella Nipotina earned connections $7 million with the victory.

Godolphin colt Traffic Warden was a late scratching after becoming fractious in the starting gates.

The Everest was run for the first time as a Group 1, the official top-tier status that had been previously denied it since its inception in 2017 due to its novel slot race format.

Duke De Sessa was let go by Coffey at the 600m mark and hung on for a brilliant win.

It was Maher's second Caulfield Cup victory, eight years after his star mare Jameka won.

Maher said Duke De Sessa appreciated the soft 6 track at Caulfield.

"The horse had the right form going in. He had four 2,000-metre runs, and going to the mile and a half, and he loves a bit of cut in the track, it worked out," he said.

"How good Harry Coffey? I was talking to him after the horse's last run. He said he likes losing weight when he's got a chance.

"Fair play to him. He rode him confidently and he rode him well, and it was a pretty easy watch.

"He's a lovely horse he had a lot of ability. He was just a bit aggressive as a colt. He was gelded and he's just come back a nicer horse. The team has done a great job.

"He's got a bit of cut in the track his last couple of runs, which really helped him, and today for his grand final, spot on."

Land Legend was third home, unable to stay with Duke De Sessa when Coffey hit the button.

Coffey, who was diagnosed with cystic fibrosis at six weeks old, celebrated his 29th birthday with his first Caulfield Cup victory.

"I just couldn't believe it that he kept running and the Caulfield Cup was going to have Harry Coffey's name next to it," Coffey said.

"It's just phenomenal. It's not supposed to happen to people like myself.

"I'm considered a battler and people like to laugh about how I'm a battler and a country boy, but not many Caulfield Cups get won by country boys.

"I couldn't pull the horse up, to be honest. I just let him roll and me and him just had a little moment … I actually can't tell you the love and the happiness for how well this horse ran today."

There was drama before the race when Warmonger broke through the gates and delayed the start.

AAP/ABC