2002: two-year-old season

Spartacus made his debut on 15 May in a maiden race over seven furlongs at Gowran Park in which he started 4/5 favourite against nine opponents. Ridden by Mick Kinane he took the lead approaching the final furlong and quickly drew away to win "easily" by three lengths.^[5] In June the colt was dropped in distance and moved up sharply in class when he was sent to England for the Group 3 Coventry Stakes over six furlongs at Royal Ascot. He never looked likely to trouble the leaders and finished ninth behind his stablemate Statue of Liberty. He produced a much better effort at the Curragh in July when he finished second to Oratorio (another O'Brien trainee) in the Anglesey Stakes.

On 11 August at the Curragh the colt was stepped up again in class for the Group 1 Phoenix Stakes in which he was partnered by Colm O'Donoghue. He was the least fancied of the Ballydoyle quartet, starting ay 16/1 whereas Hold That Tiger was made 11/10 favourite with Marino Marini (Marble Hill Stakes) on 7/2 and Oratorio on 9/1. The best fancied of the other five runners were the fillies Cassis (runner-up in the Cherry Hinton Stakes) and Luminata (Silver Flash Stakes). Spartacus led from the start before giving way to Marino Marini a quarter mile from the finish but then rallied to regain the advantage inside the final furlong. He kept on well in the closing stages to win by half a length from Marino Marini with the outsider Polar Force a short head away in third.^[6][7] After the race Aidan O'Brien aid "It's not a huge surprise. We've always thought very highly of him. He went from winning a seven-furlong maiden at Gowran Park to the Coventry at Royal Ascot, where he was all at sea back to six furlongs on very fast ground which he had never worked or raced on. Johnny Murtagh rode him that day and said it was like riding a horse in his first piece of work. He's obviously an improving colt and should stay further."^[8]

After missing a scheduled run in the National Stakes Spartacus was sent to France for the Grand Critérium at Longchamp on 8 October and finished seventh of the fourteen runners behind Hold That Tiger. Two weeks after his defeat in Paris attempted to end his season with a second Group 1 success when he travelled to Italy ad started 1.3/1 favourite for the Gran Criterium over 1600 metres at San Siro Racecourse in Milan. The best of his rivals appeared to be the British challengers Excelsius and Tacitus (second in the July Stakes) and the locally trained and Balkenhol. The twelve runners were reduced to nine after 400 metres when Chippolino fell and brought down Winning Dash and Silverboat.^[9] Spartacus led early before settling in third and then regained the lead in the straight. He stayed on well and won by three lengths from the Mick Channon-trained outsider Checkit.^[10]

2003: three-year-old season

Spartacus missed the spring of 2003 and returned after an absence of eight months in the Grand Prix de Paris over 2000 metres at Longchamp on 22 June. He raced in third place for most of the way but faded badly in the straight and finished last of the eleven runners. In the Sussex Stakes at Goodwood a month later he disputed the lead in the early stages before dropping away in the straight and finishing last of the nine runners, ten lengths behind the winner Reel Buddy.^[11]