US hero primed for a marathon effort

Despite the massively increased distance, open-water swimming usually comes down to a sprint finish, with less than eight seconds covering the medal positions at Beijing, London and the 2013 world championships.

So when young American Jordan Wilimovsky won last year’s world championships by more than 12 seconds – the largest winning margin in the event’s history – it marked him out as the obvious favourite for the Rio Games.

The 22-year-old finished fourth in Saturday night’s 1,500m in the pool – missing a medal by 4.17s (4.91s separated gold and silver) – and that performance makes it difficult to see anyone else standing on the top step of the podium today.