Jazz Carlin won her second Olympic silver medal as Katie Ledecky stormed to 800 metres freestyle gold in a world record time.
Carlin, 400m silver medallist behind Ledecky last Saturday, clocked eight minutes 16.17 seconds to take silver ahead of Boglarka Kapas of Hungary, who finished in 8mins 16.37.
Ledecky was always likely to win and did so in stunning fashion, breaking her own world record to triumph in 8:04.79.
It was Ledecky’s fourth gold of the Games and fifth in all as she successfully defended the title she won at London 2012, when she was 15.
Welshwoman Carlin said: “If someone had told me four years ago that I would be stood on a podium twice with two silver medals I would have said there is no way.
“It has taken a lot of time to get here and there have been times when I haven’t believed in myself but my family and the all of the support staff around me have believed in me from the bottom.
“I feel very lucky to have gotten on the podium again. When you are racing an 800m and there is someone that far ahead swimming an incredible race, you focus on yourself.
“The rest of the field was Olympic medallists and world medallists so I knew it was a tough field as well as Katie being in the race.
“I have got great googles so I could see around me. The 800m is a tactical race, you have got to be aware of everyone in the pool who could make their move at any time. It was great to be part of such an incredible race.
“Since I was a young girl it has been a dream to go to an Olympics and to finally be here is a dream come true but to be on the podium twice with two silver medals definitely hasn’t sunk in, it feels a bit surreal.”
Michael Phelps, meanwhile, missed out on a 23rd Olympic gold medal by finishing in a three-way tie for second in the 100m butterfly.
The 31-year-old, who plans to retire after the 2016 Games, finished behind Joseph Schooling, with the Singaporean swimmer winning gold in 50.39 seconds.
Phelps touched the wall in his final individual event second in 51.14 - as did Chad le Clos of South Africa and Laszlo Cseh of Hungary.
It left the question over whether Rio 2016 organisers would have three silver medals for one event.
Of his 27 Olympic medals, only five have been off the top step of the podium, with three silvers and two bronze medals.
Phelps has one more opportunity to sign off with a gold medal - in tonight’s 4x100m medley relay.
Defeat in the 200m fly to Le Clos at London 2012 inspired him to make a comeback and earlier this week Ryan Lochte - his long-time friend and team-mate - said he expected Phelps to be at Tokyo 2020.
Like Le Clos, Schooling grew up as an admirer of Phelps and there were pictures on social media of the Singapore swimmer, now 21, posing with the American eight years ago.
Katinka Hosszu of Hungary was bidding for a fourth gold in the women’s 200m backstroke.
Hosszu led for 175m but was hauled in by Maya Dirado as the American won by 0.06 in 2:05.99.
Hosszu finished in 2:06.05, while Canada’s Hilary Caldwell was third in 2:07.54.
Anthony Ervin, the 35-year-old American, won gold in the 50m freestyle, 16 years after taking the title for the first time.
Ervin returned from retirement and won gold in 21.40, as defending champion Florent Manaudou of France finished 0.01 behind in second.
Nathan Adrian, Ervin’s fellow American, finished third in 21.49 and Britain’s Ben Proud was fourth in 21.68.
Fran Halsall will hope she escapes the fourth curse in the final of the 50m freestyle tonight after qualifying fourth fastest.
The 26-year-old, a multiple medallist at world, European and Commonwealth level, is chasing her first Olympic medal.
Halsall’s night did not go to plan out of the pool after the bus she was on from the athletes’ village went the wrong way, reportedly heading to the Olympic Stadium across the other side of the city.
“I was involved in transport issues, there were about three of us in that race,” said Halsall. “But it hasn’t derailed me, I’ve done it under the stress, made the final, so less stress tomorrow night, the bus turns up, it will be all good.”
Adam Peaty’s bid for a second Olympic gold of the Rio Games remains on course after Great Britain qualified fastest for the 4x100m medley relay final.
Peaty, who last Sunday won 100m breaststroke gold, combined with Chris Walker-Hebborn, James Guy and Scotland’s Duncan Scott to clock a British record 3mins 30.47secs in yesterday afternoon’s heats.