Champion trainers Aidan O'Brien and Willie Mullins don't mind being upstaged by a 24-year-old rookie in the Irish Melbourne Cup trifecta.

To be sure, Joseph O'Brien did it on his first attempt.

Sure, the former jockey has only been training racehorses for a bit over a year.

Sure, in the father-and-son finish it was the younger O'Brien who prevailed.

Aidan would have been shouting as loud for his son as for himself.

"He was over the moon," Joseph said about the phone call to his dad, who wasn't at Flemington because of Breeders' Cup commitments in America.

"He was delighted."

Joseph couldn't quite believe his luck, after Rekindling overhauled his champion Irish flat trainer dad's Johannes Vermeer in the closing stages.

"It hasn't sunk in to be honest.

"I'm over the moon."

Mullins, Ireland's champion National Hunt trainer, was left with third for Max Dynamite, the 2015 Cup runner-up.

"It's fantastic for Joseph, so well done to him. It's an exciting start to his career.

"I don't think Aidan will begrudge him that one. He was probably shouting for him as much as his own. Or probably more."

The Irish were the first to claim the Melbourne Cup for a northern hemisphere-trained horse, thanks to Dermot Weld with Vintage Crop in 1993 and again with Media Puzzle in 2002.

But an Irish trifecta infront of a 90,000-plus crowd at Flemington is something else.

"It's a huge achievement," Mullins said.

"It's a big undertaking coming down here and being Irish, we're willing to travel and take the chance maybe. And it's paid off."

Retired Melbourne businessman Lloyd Williams, already the most successful owner in Cup history, took the quinella in winning his record sixth Cup

"It's absolutely a dream. I'm so thrilled."

Williams had already predicted the younger O'Brien will be one of the world's leading trainers, even before the Cup win.

"I'm very egotistical and I've been saying that for some time, that he's going to be the leading trainer in the world."

Williams, who has been in love with Australia's most famous race for 70 of his 77 years, has seen many fantastic trainers try to win the $6 million Cup and fail.

"It's extraordinary, absolutely extraordinary," he said of Joseph's first-up success.

"It's close to being able to walk on water I think.

"He's going to emulate his father and maybe more."

The Irish trifecta capped off a strong performance for a record-equalling 11 international runners, who took nine of the first 11 placings.

Jockey Corey Brown didn't need the luck of the Irish to win a second Melbourne Cup.

He had his own lucky charm - a gold nugget a young property developer mate tripped over that he now carries everywhere with him.

"Everything he touches turns to gold," Brown said

"He told me that it's for luck. If that's what worked, so be it.

"He won't be getting it back."