[3] Supremacy's dam Triggers Broom showed no racing ability, failing to win or place in her five starts,[4] but was a half-sister to the Champions Mile winner Xtension.

She was a female-line descendant of the British broodmare Bongrace, making her a distant relative of Blushing John, Royal Diamond and Hurricane Run.

"[8] Kirby was again in the saddle when Supremacy was moved up to the highest class to contest the Group 1 Middle Park Stakes at Newmarket Racecourse on 26 September.

Kirby again adopted front-running tactics and Supremacy was never headed, repelling a sustained challenge from Lucky Vega to win by half a length.

"[10] In the official European classification of for 2020 Supremacy was given a rating of 118, making him the second best two-year-old of the season two pounds behind the top-rated St Mark's Basilica.