Ontario bids to continue Aidan O'Brien’s recent domination of the tote+ Biggest Dividends At tote.co.uk Dee Stakes at Chester on Thursday.

The Ballydoyle handler has saddled six of the last eight winners of the recognised Derby trial, with multiple Group One winner Circus Maximus landing the most recent renewal in 2019.

Although this year’s candidate has managed only one victory from eight previous starts, he has run some fine races in defeat, perhaps most notably finishing a close-up third behind Derby prospect and subsequent Group One scorer Mac Swiney in the Futurity Stakes.

Ontario made a promising start to the new campaign when third behind the Queen’s Tactical in the Free Handicap at Newmarket three weeks ago, and steps up to an extended mile and a quarter for the first time on the Roodee.

Ontario will be ridden by Ryan Moore, who told Betfair: "He looks to hold pretty strong claims.

"He finished a good third in what appears a decent Free Handicap on his return, and his pedigree would give you every encouragement that the step up from seven to 10 furlongs or so here will suit this Galileo colt a lot better.

"He finished second in a Royal Lodge at two, while he also finished third to Mac Swiney in soft ground in the Futurity at the Curragh, so you’d have to be pretty hopeful, though his draw (stall seven) could have been better, obviously."

The likely favourite for the Listed contest is the Charlie Appleby-trained Yibir, who was narrowly beaten in the Sandown Classic Trial on his reappearance.

A full-brother to top-class racemare Wild Illusion, the son of Dubawi is fitted with cheekpieces for the first time.

"He’s sharpened up for that run at Sandown quite noticeably at home," said Appleby.

"We’re putting the cheekpieces on him, just because he’s got similar characteristics to his sister – it’s not that he’s ungenuine, it’s just to keep him focussed.

"We didn’t want to put the cheekpieces on and step him up to a mile and a half at the same time, so we opted to keep him to 10 furlongs."

Michael Stoute trained the last horse to complete the Dee Stakes-Derby double in 2003 victor Kris Kin.

This year the master of Freemason Lodge is represented by Maximal, who filled the runner-up spot behind Appleby’s Hurricane Lane in a competitive conditions race at Newbury last month.

Teddy Grimthorpe, racing manager for owner-breeders Juddmonte, said: "He ran a good race at Newbury and has come out of it well – he’s been straightforward since.

"It’s a good spot for him. He’s a neat horse and I think he will handle the track.

"He will need to have come on as this looks a pretty competitive race all round, I would say.

"The going is a little bit of an unknown, but he is by Galileo, so hopefully he’ll cope with it."

The most inexperienced horse in the field with just two runs under his belt is Andrew Balding’s Foxes Tales.

Second on his racecourse debut at Kempton in December, the Zoffany colt went one better on his three-year-old debut at Newbury.

The trainer’s wife, Anna Lisa Balding, said: "He’s a really nice horse, Foxes Tales – he’s so good looking. He’s done nothing wrong so far and has physically gone the right way.

"Andrew has been quite patient with him and the jockeys who ride him at home really like him."

Earlswood (Johnny Murtagh), El Drama (Roger Varian) and outsider Luther Cee (Henry Spiller) are the other hopefuls.