Venetian Sun's highly-anticipated run in the July Cup is in doubt due to concerns over the going.
Trainer Karl Burke says that connections will make a final decision on Saturday morning after he has walked the course.
His superstar filly, co-owned by Brighton & Hove Albion boss Tony Bloom, is seeking a Group 1 double after she strode to an impressive success in the Commonwealth Cup at Royal Ascot.
The going was described as good to firm throughout action on the opening day of the Newmarket July Festival, but with little chance of rain and hot temperatures forecast for Friday and Saturday, conditions are only expected to get quicker.
"We'll be keeping a close eye on what they do with the watering and how the ground rides today; I'd imagine it's going to quicken up again," Burke told reporters on Friday morning.
"We'll walk the track in the morning before a final decision is made whether she can run or not.
"She's better with a little bit of cut in the ground – she proved that at Haydock [when winning the Sandy Lane] – and it's her first time taking on the older horses, so we want to have everything safe for her."
The going at Royal Ascot when Venetian Sun landed the Commonwealth Cup last month was advertised as good to firm.
Success at the Berkshire track took her Group 1 tally to two after edging out subsequent Irish 2,000 Guineas winner Gstaad in the Prix Morny during her juvenile season.
Despite her glittering CV, this weekend's feature July Cup may prove to be her toughest assignment yet at sprint trips.
Three Group 1-winning sprinters from Royal Ascot, including Venetian Sun, will head to post at Britian's Flat racing HQ. Mission Central, winner of the King Charles III Stakes and Almeraq, winner of the Queen Elizabeth II Jubilee Stakes, both take up prominent market positions.
As well as the big three, Japanese challenger Santono Reve will bid to avenge his unfortunate second at Ascot last month.
