The G1 Gold Cup (3991m) holds a special place at the heart of Royal Ascot and the challenge of winning the race, run for the first time in 1807 over a distance rarely attempted, engages the minds and skills of the finest trainers.

Irish trainer Aidan O’Brien has won the Gold Cup a record eight times and has chosen Emily Dickinson to try to make it nine.

The four-year-old mare would seem to face a formidable task against the market leaders, Coltrane and Eldar Eldarov. Emily Dickinson has won only three of her 13 races, not won above Group 3 level and was fifth behind Eldar Eldarov in last year’s G1 St Leger (2905m) at Doncaster.

Yet if O’Brien believes that Emily Dickinson is the right horse, his opinion must be respected. “We think she stays very well,” he said, “and we’re excited to see what she might be able to do over a trip like this.”

When Emily Dickinson was stepped up to 3200m she powered clear in the G3 Loughbrown Stakes at the Curragh. The further they went, the better she went.

Her recent defeat when odds-on favourite for a Group 3 contest over 2800m has not dented O’Brien’s confidence. He said, “There was no pace in the race and she was left in front which wasn’t ideal. Everything has gone really well since, which is the main thing.”

In the Gold Cup, the question is always, “Will the horse stay the near 4000m trip?”

Eldar Eldarov, trained by Roger Varian, won last year’s G2 Queen’s Vase (2831m) at Royal Ascot before the St Leger. On his return last month he came from a long way back to finish a close second in the G2 Yorkshire Cup (2771m) at York.

Varian said, “Once you go beyond 3200 (metres) with these Flat-bred horses you are taking a step into the unknown but we believe he’ll get the trip and might even improve for it. Every time he’s run he’s looked as if he’s only just getting going when the line comes. We’re looking forward to it.”

Andrew Balding has no such concern about Coltrane, who won last year’s Ascot Stakes over the same trip as the Gold Cup and this year won the G3 Sagaro Stakes (3190m) at Ascot impressively.

“The good thing about Coltrane is we know he stays and we know he loves the track,” Balding said. “That has got to be a massive plus. I thought his win in the Sagaro was his best performance ever and he seems in great heart.”

Opponents will insist that it is not a three horse race. Frankie Dettori’s many fans will be backing the unbeaten Courage Mon Ami, unraced beyond 2800m. There will be support for Yibir, unraced beyond 2600m, for Subjectivist, winner of the race in 2021 and striving to recapture his best form after a long break. Then there is Trueshan, a proven stayer with a fine record at Ascot for whom the more rain the better.

An intriguing and exciting contest.