Jockey Joseph O'Brien is praying the rain stays away from Ascot to allow St Nicholas Abbey show his true brilliance in Saturday's King George VI And Queen Elizabeth Stakes.

The six-year-old has finished third in the last two renewals of the midsummer showpiece and returns to England fresh from his third triumph in the Coronation Cup at Epsom - his sixth Group One success.

There is little doubt the son of Montjeu's devastating acceleration is most potent on a sound surface.

O'Brien admits he would be concerned if conditions deteriorate during the week.

"The quicker the ground the better for my horse," he said.

"On good to firm, quick ground I'd be very happy.

"If it got much slower than good, I'd have a little worry."

Ascot clerk of the course Chris Stickels is anticipating some rainfall at the track this week, but is unsure what volume to expect.

"There are some thunder showers forecast for tomorrow, but is hard to predict how much rain we'll actually get," he said.

"There is a very good chance we'll get some rain, so we're not planning to water tomorrow and we'll just have to wait and see how much arrives.

"It looks like being a drier day on Wednesday and then we could get more thundery showers from Thursday right through until Sunday.

"Tomorrow looks like being the most significant day in terms of rain, so we'll take a view after that."

St Nicholas Abbey is one of 11 horses in contention, with trainer Aidan O'Brien also having left in Chamonix and Ernest Hemingway.