Frankel is a "very unlikely" participant in the Lockinge Stakes at Newbury on 19 May, according to racing manager Teddy Grimthorpe.
The horse sustained a "superficial" leg injury when working in Newmarket and a further scan is needed to determine the full extent of the problem.
Grimthorpe told At The Races: "It'd be too early to rule him out of Ascot [but] Newbury would be very unlikely."
The Sir Henry Cecil-trained colt will have the second scan next week.
Grimthorpe, racing manager to owner Khalid Abdullah, added: "The initial scan, which is done on portable scan, showed no damage and no hole, which is positive, which led us to believe and hope it was superficial or just a minor injury.
"But obviously, with a horse of this nature, or any horse actually, we have to be incredibly careful, especially with injuries of this type in this area.
"He's getting the best care he can get at the moment and he'll go into the Equine Hospital in Newmarket and have a scan on a big machine which will tell us definitely if there is any damage.
"We are all very hopeful for a positive outcome and we'll have to see how that pans out."