Thunderous won the rescheduled Dante Stakes at York to complete a 59-1 double for trainer Mark Johnston and jockey Franny Norton.
The 13-2 chance beat 8-11 favourite Highest Ground by a neck after Rose Of Kildare won the Musidora Stakes.
Usually a leading Derby trial, the Dante was postponed from May because of the coronavirus pandemic.
Jockey Hollie Doyle won a Group Two race for the first time, with Dame Malliot at Newmarket.
The 8-1 chance, trained by Ed Vaughan, took the Princess of Wales' Stakes.
Doyle, who rode her first Royal Ascot winner in June, broke the record for victories by a female jockey last year and told BBC Sport at the time that a Group winner was her next target.
With the Derby having being won by Serpentine on Saturday, the only British Classic option left for Thunderous is the St Leger at Doncaster in September.
A potential Classic prospect next year is Tactical, a Royal Ascot winner owned by the Queen who followed up with victory in the July Stakes as jockey William Buick claimed a treble.
The two-year-old victor, a son, of Sussex Stakes winner Toronado, is likely to head for the Prix Morny at Deauville next.