Frankie Dettori has reinforced he is the king of Ascot with a memorable double highlighted by Crystal Ocean in the Prince Of Wales's Stakes.

It was the ebullient jockey's 62nd career winner at the Royal meeting, after he had opened his account for 2019 on Raffle Prize in the Queen Mary Stakes on Wednesday (Thursday AEST).

Even though he has been one of the most sought-after jockeys in the world for the past 30 years, he revealed he approached trainer Sir Michael Stoute for the ride.

"As soon as I knew Enable wasn't going to run in the Prince Of Wales's Stakes and was going to wait for the Eclipse, I rang Sir Michael's office and said I was available for the ride," Dettori said.

"He got back to me the same afternoon and I was delighted he said I'd got the ride."

On a day when stamina was crucial with the rain pouring down during the 10-furlong (2000m) Group One race, he had Crystal Ocean in the perfect position.

The talented five-year-old is arguably better over a mile-and-a-half (2400m) and his ability to stay was a factor as Dettori took him to the front early in the straight to put pressure on his rivals.

It was a winning move and Crystal Ocean (3-1) galloped on resolutely to take the honours for owner-breeder Sir Evelyn De Rothschild and win at the top level for the first time after being runner-up three times.

The Aidan O'Brien-trained 13-8 favourite Magical was 1-1/4 lengths second.

Dettori admitted he had concerns the ground might be too soft.

"I was worried about the rain as his best form is on firm, but I kicked on the turn and used his stamina. He galloped all the way to the line," he said.

"He was still full of running and I didn't feel she (Magical) would get past me. Everything went to plan."

Crystal Ocean has entries in both the Coral-Eclipse Stakes at Sandown, where he could clash with Enable, and the King George VI And Queen Elizabeth Stakes next month.

"Crystal Ocean is a high-class horse and I am delighted to have won a Group One with him now. He is just a very admirable racehorse. It's marvellous to train a Group One horse like this," Stoute said.

Dettori's first win on the Mark Johnston-trained Raffle Prize (18-1) was a little more unexpected.

Wesley Ward's Kimari was in front with two of the five furlongs left to run, but Raffle Prize was just starting her move and swept through to edge into the lead.

Kimari tried hard but could not get back in front, with Raffle Prize prevailing by a head.

"No disrespect to Lester Piggott, but isn't Frankie Dettori just the greatest jockey?" Johnston said.