World Racing Weekly: Aidan O’Brien, Diamond Necklace & Overnight

Diamond Necklace For O’Brien’s French Connection

Ireland’s champion trainer Aidan O’Brien is aiming to nail a French Derby-Oaks double this weekend, with Diamond Necklace his standout in the G1 Prix de Diane to follow-up the Ballydoyle stable’s dominant result in the G1 Prix du Jockey Club two weekends ago. 

Constitution River led home an O’Brien-trained 1-2-3 in the Jockey Club, giving the trainer a third win in France’s Derby and now he is seeking a second French Oaks win, following Joan Of Arc in 2021. 

His stable’s Jockey Club win was lauded as a tactical masterclass after Montreal set a good pace that set-up Constitution River to close and pass him under Ryan Moore, with Hawk Mountain staying on gamely for second.  

It’s a common sight, a Ballydoyle runner leading, even haring off well clear of the field, but O’Brien played down the tactical element.  

“It’s always straightforward and I think it suits everybody when there’s an even pace,” O’Brien said. “I don’t think it’s ever about tactics. All we ever want is an evenly run race and then everybody finds out where they stand afterwards and whether their horse gets the trip or doesn’t get the trip.

“And when the pace is like that, obviously, people and horses aren’t on top of each other, really. That’s the only reason ever. And I think everybody kind of knows where they stand when there’s an evenly run race.”

That approach has helped O’Brien win 100 classics in Ireland and Britain – the latest being Christmas Day in the Derby at Epsom – but he has never been as dominant a force in the French classics, in which he has 12 wins. But seven of that dozen have come in the last five years. 

And after the unbeaten Diamond Necklace gave him his first G1 Poule d’Essai de Pouliches win in May, O’Brien is looking to make it three wins in France’s four classics this year alone.  

“With Diamond Necklace, since she won the French Guineas, everything has gone well,” O’Brien said, referencing her three-length win on heavy going at Longchamp. 

“I’ve been very happy with her. The plan was always, if everything went well in the Guineas, to come back here. Everything has been very good since her last victory. I think she’s even better on better ground.”

Diamond Necklace is a daughter of O’Brien’s first French Derby winner, St Mark’s Basilica, and he sees similarities to her sire, who was a star at around 2000m with further wins in the G1 Eclipse Stakes and G1 Irish Champion Stakes. 

“We always thought a mile and a quarter shouldn’t be a problem to Diamond Necklace,” O’Brien continued. “Obviously, we’re going to learn more on Sunday.

“She’s good, very straightforward. She’s well balanced. She’s a medium-sized filly and usually travels well in her races. She’s very like her sire, St. Mark’s Basilica: when he went up to a mile and a quarter, he improved again and everything she does is very like him, really.” 

The stable had four fillies still in the mix at Tuesday’s forfeit stage, but the trainer said only one is likely to accompany Diamond Necklace in the 2100m race. 

“It could be Moments Of Joy, we’re thinking of running,” he said. “She had a couple of choices: the Epsom Oaks, Ascot for the Ribblesdale, and Chantilly. So we’re thinking at the moment she might go to the Diane. 

“We think there’s more improvement to come from her, and we think she’d like the trip, and we think she’d like the track as well. I think she’d like light and nice ground. I don’t think she’d be mad about soft ground. She’s a very good mover.”

The Diane also looks set to include the G3 Musidora Stakes second Felicitas, the Pouliches third Green Spirit and the Karl Burke-trained Evolutionist, second in the G1 1,000 Guineas at Newmarket, England last time.

“She’s getting stronger, she’s certainly a stronger filly now than she was in May at Newmarket,” Burke said.

He also expressed “90 percent” confidence in Evolutionist staying the distance, but also a small “regret” that perhaps the filly should be heading to Royal Ascot for the Coronation Stakes at a mile after Shane Foley was “very taken” with her gallop Tuesday morning. 

“We’ll ride her a little bit differently, we won’t ride her as aggressively as we did in the Guineas,” Burke said. “I don’t know how we get Diamond Necklace beat, but you should never be afraid of one horse.”

This Week In Horse Racing History

It was on June 8, 1957 that Queen Elizabeth II led in her first classic winner, after the Noel Murless-trained and Lester Piggott-ridden Carrozza won the Oaks at Epsom. Piggott and Murless had won the Derby two days prior with the Sir Victor Sassoon-owned Crepello. Carrozza was the first royal classic winner at Epsom in 48 years, since Edward VII’s colt Minoru won the 1909 Derby. The filly was owned on a lease from the National Stud.

Steve Cauthen became the youngest jockey to win the U.S. Triple Crown on June 10 1978 when at age 18 he rode Affirmed to victory in the Belmont Stakes. 

On June 11, 1898 Willie Simms became the only African American jockey to win the Preakness Stakes, making him the only one to win all three Triple Crown races, too. And, exactly 21 years later, on June 11, 1919, Sir Barton became the first U.S. Triple Crown winner.

Idol Horse Reads Of The Week

The standout this week is Michael Cox’s excellent profile of John Size, a fascinating and insightful read about one of horse racing’s greatest living trainers, a man who is always thinking about the horse, but is also perhaps one of the sport’s most misunderstood enigmas.

Michael Cox

Tap, Tap, Tap: John Size, 25 Years And Still Intrigued By Horses

Zac Lloyd had his first two wins in Britain last week and will ride at Royal Ascot next week. Adam Pengilly caught up with Australia’s rising star jockey last August and talked about the fine line of confidence, keeping out of the stewards’ room, and his father’s inspirational perseverance.

Adam Pengilly

“You’ve Got To Have Confidence, Otherwise You’ll Get Killed Out There”: Zac Lloyd Rides The Fine Line

This week’s Tokyo Derby at Oi served as a reminder that it’s 16 months since the “King of Oi”, the incomparable Fumio Matoba retired from race-riding and almost two years since he last thrilled the Tokyo City Keiba crowd with his “Matoba Dance”. David Morgan’s article from the time of the retirement announcement takes a brief look back at his incredible career.

David Morgan

No More ‘Matoba Dance’ As Oi’s Iconic Jockey Retires

And with the news this week that Japan is sending a top contender, Masquerade Ball, to the King George VI & Queen Elizabeth Stakes at Ascot, here’s a look back at a feature from last summer, which explores the importance to Ascot, York, Goodwood and Leopardstown racecourses of Japanese and other intercontinental participation in their major races.

David Morgan

Playing The Long Game: Ascot, York, Goodwood and Leopardstown Know The Value In Wooing The Japanese

Racing Photo Of The Week

Date
7 June, 2026

Photographer
Photo by @JunKeiba3F

Location
Tokyo Racecourse

For more from @JunKeiba3F
Follow on X

CLOSE

Global Blackbook

Three Listed races for three-year-olds at Longchamp last Sunday are all worth another look, but from that trio of winners, we’ll put our focus on the homebred Wertheimer family colt Overnight who won the Prix Ridgway over 2000m by three lengths, the same race Daryz won last year en route to Prix de l’Arc de Triomphe glory. 

This was Overnight’s second win, having been beaten into second place on debut back in March, and he is a racehorse on an eye-catching upward trajectory. The white-faced chestnut with a long white stocking on his off-fore leg has been the odds-on favourite each time he has raced, suggesting he is held in good regard at home. This time Overnight travelled smartly, shifted through the gears a little immaturely, but once he found his long stride he drew three lengths clear for a win that suggested he might well have the potential to continue climbing into the high grades. 

The Andre Fabre-trained colt traces back to the G1 Prix de l’Arc de Triomphe winner Gold River, his fourth dam, and despite being by Night Of Thunder – a stallion yet to produce a top-class 2400m runner – he races like he may stay farther and holds entries in the G1 Grand Prix de Paris and the Prix de l’Arc de Triomphe at a mile and a half, though he is expected to go next to Saint-Cloud for the G2 Prix Eugene Adam on 28 June.  

Fabre has long been a master of bringing along a three-year-old to peak when the time is right, whether that be in the spring and early summer classics or later in the year when they have reached the required maturity. His Juddmonte home-bred filly Dispatches also looked better than the grade when a tidy winner of the 2000m Prix Melisande, making it three wins from four starts.

And the third of the Listed winners to keep an eye on is Godolphin’s Fortuna Diamond – another by Night Of Thunder – who has won all three starts since she switched, unraced, from Charlie Appleby to Henri-Alex Pantall’s stable. But Overnight is the standout.

Look at that stride! 👀

Daryz took the Prix Ridgway before going onto bigger and better things last year and Overnight follows in his footsteps with an impressive display at ParisLongchamp… 🇫🇷 pic.twitter.com/XazBDZnUMp

— At The Races (@AtTheRaces) June 7, 2026

World Horse Racing Calendar: What’s Coming Up

The Stradbroke & Q22
Eagle Farm, Australia, June 13

James McDonald is set to ride the Chris Waller-trained mare Fangirl in the 1400m G1 Stradbroke Handicap at Eagle Farm on Saturday, as long as the track is not too wet. The race could also feature Melbourne Cup-winning rider Jamie Melham who has opted to side with Sixties, currently the first emergency and in need of one horse to come out in order to get a run. The race is also set to feature local hero Rothfire, as well as Private Eye and the recent Kingsford-Smith Cup winner Headley Grange. Ciaron Maher took Jimmysstar out but the trainer has Warnie and Another Wil in contention. The day also features the G2 Q22 over 2200m and the G1 JJ Atkins Stakes over a mile for two-year-olds.

Royal Ascot
Ascot, England, June 16-20

The five-day Royal Ascot meeting features a wealth of high-class racing, the highlights being the G1 Prince Of Wales’s Stakes in which last year’s winner Ombudsman could clash with the Arc winner Daryz, the G1 Queen Anne Stakes, G1 Gold Cup, G1 St James’s Palace Stakes, G1 Coronation Stakes, G1 King Charles III Stakes, G1 Queen Elizabeth II Jubilee Stakes and G1 Commonwealth Cup. 

Irish Derby Day 
Curragh, Ireland, June 28

The Irish Derby was first run in 1866 and it is not uncommon to see the Derby winner at Epsom head to Ireland to attempt the Derby double, so this year the Aidan O’Brien-trained Christmas Day could attempt the double. Orby in 1907 was the first to achieve that feat and last year saw Lambourn become the latest. O’Brien has won the Irish Derby an incredible 17 times, the first being Desert King in 1997.

Durban July Day
Greyville, South Africa, July 4

The Durban July is South Africa’s pinnacle mid-year contest but longtime leading fancies See It Again and Eight On Eighteen were scratched this week after disappointing runs in last weekend’s G1 Gold Challenge. That duo’s trainer Justin Snaith has six others still in the list, though, including Gold Challenge runner-up Legal Counsel and the G1 Cape Derby winner Wish List who completed a four-timer when she won the G2 Woolavington 2000 last time.

Eclipse Stakes Day
Sandown, England, July 4

The Eclipse Stakes gives the British and Irish middle-distance three-year-olds their first big opportunity to take on their elders. The 10-furlong contest has been won by some of the sport’s great champions. Last year’s second Ombudsman might face the recent G1 Prix du Jockey Club winner Constitution River, though the latter’s connections are also considering alternative options.

Adam Pengilly

Hugh Bowman on Winx, Pressure, and Purpose: “Nothing Keeps You Motivated Like a Good Horse”

Michael Cox

Self-Made: How Zac Purton Built The Greatest Career In Hong Kong Racing History