[6] On 11 October at the Curragh the colt was stepped up in class but dropped in distance for the Group 3 Anglesey Stakes over six and a half furlongs and went off the 6/1 third choice in the betting behind the Aidan O'Brien-trained contenders Preamble and Lippizaner.
Ridden by Gary Carroll, A Case of You disputed the lead from the start, gained the advantage at half way and stayed on well in the closing stages to win by one and a quarter lengths from Lippizaner.
"[8] Before the start of the 2021 season A Case Of You was bought by Gary Devlin and transferred to the training stable of Adrian McGuinness at Lusk, County Dublin.
[9] In the following month A Case of You started favourite for the Listed 2,000 Guineas Trial Stakes over seven furlongs Leopardstown Racecourse but after being in contention for most of the way he hung badly to the right in the straight and came home last of the twelve runners behind.
[10] Whelan was again in the saddle when A Case of You contested the Group 3 Lacken Stakes over six furlongs at Naas Racecourse on 16 May and started second choice in the betting his old rival Lippizaner.
"[12] A Case of You moved to the highest level for the Group 1 Commonwealth Cup at Royal Ascot in June but finished eleventh of the fifteen runners after losing a shoe in the race.
[13] Following a break of over seven weeks, the colt returned in the Group 3 Phoenix Sprint Stakes over six furlongs at the Curragh on 8 August when he was matched against older horses and came home third behind the five-year-old Gustavus Weston.
Ridden by Whelan, he was towards the rear in the early stages before producing a strong late run to finish second, half a length behind the six-year-old mare Romantic Proposal.
The five-year-old mare Air de Valse had opened up a clear advantage but the Irish colt maintained his run, caught the leader on the line and won by a short head.
"[16] As McGuinness had suggested, A Case of You ended his season with a trip to California to contest the Breeders' Cup Turf Sprint over five furlongs at Del Mar Racetrack on November 6.