Diana Willson rode Chianti Rosso in the individual and team three-day event at the 1968 Mexico City Olympic Games, placing 26th in the individual competition.
The endurance day at Avandaro was among the most testing in Olympic eventing history. The cross-country course carried 35 obstacles, and torrential rain swelled the stream at the 34th into a torrent twelve metres wide. Willson brought Chianti Rosso home, and in the concluding show jumping phase the pair produced one of only two clear rounds of the competition, matched on the day by Jean Sarrazin of France.
She was one of two Irish riders to complete the three days, alongside Juliet Jobling-Purser, who placed 7th. The Irish eventing squad at Mexico City also included Penelope Moreton and Tommy Brennan. Willson rode out of the Kildare Hunt.