On 19 August, it was announced that Irish had accepted a challenge to run Papyrus against "the best American horse" for a prize of £4,000. Later that month the American Jockey Club announced that the race would take place on 20 October and that the prize would be $100,000, with a consolation prize of $2,000 for the beaten horse. The Kentucky Derby winner Zev was eventually selected as the American representative on 6 October. Papyrus's first race after the Derby was the Duke of York Stakes at York on 28 August. He was beaten a short-head by the front-running Craigelyr, but was awarded the race after Donoghue lodged an objection against the winner on the grounds of "boring". Less than two weeks later Papyrus started favourite for the St Leger at Doncaster. He took the lead in the straight and got the better of a prolonged struggle with Parth, but was caught in the closing stages and beaten by Lord Derby's filly Tranquil. During the race Papyrus was "struck into" by another horse and returned bleeding freely from several cuts to his legs, one of which narrowly missed a tendon.