The Scat Daddy colt was sent off the 7-4 favourite to take his 100 per cent record to three in the Group Two contest over a mile, but he blotted his copybook with an uncharacteristic performance.
Gosden reports Beatboxer to be none the worse and explained the likely reason for the below-par effort.
“He seems fine at home. He got a bump coming out of the gates and tried to do the whole thing on one breath. He just got tense, which is not the way to race,” said the Newmarket handler.
“He will probably run again, but I’m not sure where that will be.
“He cantered on Saturday morning and seemed fine.”
Beatboxer has an early-closing domestic entry in the Vertem Futurity Trophy at Doncaster on October 27.