Jazz Carlin, who prepared in an oxygen tent, was breathing in the rarefied air close to the Olympic summit here with her second silver medal of the Games.

The British swimmer emulated one unquestionable great, Michael Phelps, on the night, though she could not match another possible great, Katie Ledecky.

It was the 19-year-old Ledecky, from Washington DC, who won her fourth gold of these Olympics and fifth in all. It came in the women's 800 metres freestyle, in which she beat Carlin by more than 11sec in a world record time of 8min 04.79sec.

Carlin's latest comes after a similar story over 400m. In both contests she was leading the clash of mortals – those behind Ledecky. It was a tough contest between her and Hungarian Boglarka Kapas, but Carlin gamely held on for silver.

Carlin, 25, was delighted to have made up for the agony of missing out on London four years ago after she struggled to throw off glandular fever.

'I thought of stopping swimming altogether, so to have come back at Rio is brilliant,' said Carlin, whose bedroom in Swansea replicates conditions at 3,500m.

The greatest star of these Games, certainly in the pre-Bolt segment, has been Phelps, who has 22 career gold medals to his name. He is a phenomenal athlete and it is a privilege to watch him.

But starting from lane two in the 100m butterfly, he took a shared silver with his bitter rival Chad le Clos, of South Africa, and Hungarian Laszio Cseh. Joseph Schooling, of Singapore, took the title. 

It was Phelps' fifth medal, including four golds, of Rio 2016 and a sixth could come on Saturday in the medley relay.

In the women's 200m backstroke final, America's Maya Dirado beat Hungarian Katinka Hosszu, who, aged 27, has been breaking world records for fun en route to three golds.