Duke of Marmalade, ridden by Johnny Murtagh for Irish trainer Aidan O'Brien, battled back in the final 30 metres to win an exciting King George VI and Queen Elizabeth Stakes at Ascot on Saturday.

It was a fourth successive Group One victory for Duke of Marmalade, the 4-6 favourite, and the 14th of the season for O'Brien, trainer for the Coolmore operation.

The colt took up the running with two furlongs (400 metres) to go and looked like winning easily only for 14-1 chance Papal Bull, the mount of Olivier Peslier, to throw down a late challenge and go a neck up in the closing stages.

But Duke of Marmalade answered the urgings of Murtagh to regain the lead and win by half a length.

Murtagh told BBC TV: "I was going so easily I was surprised to see another horse come with me. But mine has all the qualities to be great horse. He's a great battler and has a great will to win."

O'Brien, on course to beat his 2001 record when he sent out 23 Group One winners, said: "Johnny gave him a marvellous ride."

Bookmakers now quote Duke of Marmalade at 5-1 second favourite for the Prix de l'Arc de Triomphe at Longchamp in October.