[3] Mattaboy's dam Green Chartreuse won two minor races as a two-year-old in 1972[4] and was a half-sister to the Gran Premio del Jockey Club winner Stateff.
[5] As a yearling, Mattaboy was offered for sale at auction and was bought for 10,500 guineas by the bloodstock agent Tote Cherry-Downes[6] on behalf of the Indian shipping magnate Ravi Tikkoo.
In August he started odds-on favourite for the Rous Memorial Stakes at Goodwood Racecourse but was beaten one and a half lengths by the filly Integrity, to whom he was conceding six pounds in weight.
In the Mill Reef Stakes at Newbury Racecourse in September he led for most of the way before being overtaken a furlong out and was beaten one and a half lengths by Sweet Monday.
He raced towards the rear of the field as Bel Bolide set the pace before moving up rapidly on the rail to challenge the leader a quarter of a mile from the finish.
[3] Mattaboy finished unplaced on his three-year-old debut and was then sent to France for the Poule d'Essai des Poulains over 1600 metres at Longchamp Racecourse on 26 April.
In the second half of the race he made rapid progress to dispute the lead and got the better of a struggle with Bel Bolide but was caught in the final strides and beaten a neck by the favourite To-Agori-Mou.
[7] Mattaboy was scheduled to face To-Agori-Mou and Kings Lake in the St James's Palace Stakes at Royal Ascot but was withdrawn after being found to be running an abnormally high temperature on the morning of the race.
He reappeared in the Sussex Stakes at Goodwood on 29 July but ran poorly and finished seventh, thirteen lengths behind the winner Kings Lake.