The four-year-old was an impressive winner of the Hardwicke Stakes at Royal Ascot last time out, when he thrashed High Accolade by six lengths and broke the track record.
Doyen is the 5-4 favourite with Cashmans for Saturday’s race but he will be having only his third crack at Group One company after finishing fourth in the Prix de l’Arc de Triomphe at Longchamp last October and second to Warrsan in the Coronation Cup at Epsom in June.
However Dettori, who will partner Doyen in the £750,000 contest, believes that Hardwicke run represents excellent form.
“He’s very lightly raced and in the Arc he finished fourth on very deep ground, so give him a chance,” he told At The Races.
“He’s a very good horse and any horse that smashes the track record at Ascot must be respected.
“I’m hoping for a great run on Saturday.
Doyen is one of three possible runners for Godolphin as the Dubai outfit also left in Sulamani, who was a disappointing second in the Princess Of Wales’s Stakes, and likely pacemaker Lunar Sovereign at yesterday’s five-day stage.
Bandari, the Princess Of Wales’s Stakes winner, is also a possible runner in the mile-and-a-half showpiece.
The five-year-old is undergoing a renaissance this season, winning on four of his six starts after failing to get his head in front at all last campaign.
Bandari beat Sulamani by half a length at Newmarket but Angus Gold, racing manager to owner Hamdan Al Maktoum, is not certain he will run.
“I hope he will run, but I’ll be speaking to Mark Johnston and Sheikh Hamdan in the next couple of days.
“We have left him in with a view to having a good look at the race,” said Gold.
A total of 12 horses were left in the race today including the American challenger Hard Buck, who is a best-priced 33-1 with Ladbrokes.
King George VI And Queen Elizabeth Diamond Stakes betting:
Cashmans: 5-4 Doyen, 6-1 Vallee Enchantee, 7-1 Warrsan, Gamut, 8-1 Sulamani, 14-1 Bandari, 25-1 Tycoon, Phoenix Reach, High Accolade, 33-1 Hard Buck, 100-1 Lunar Sovereign
Ladbrokes: 11-10 Doyen, 5-1 Vallee Enchantee, 6-1 Gamut, Warrsan, 7-1 Sulamani, 14-1 Bandari, 20-1 High Accolade, Tycoon, 25-1 Phoenix Reach, 33-1 Hard Buck, 150-1 Lunar Sovereign.
Paddy Power: 11-10 Doyen, 11-2 Vallee Enchantee, 6-1 Gamut, Warrsan, 7-1 Sulamani, 14-1 Bandari, 16-1 Powerscourt, 20-1 Tycoon, 25-1 High Accolade, Phoenix Reach, 33-1 Hard Buck, 150-1 Lunar Sovereign.