American Michael Phelps won his 20th career Olympic gold medal on Tuesday, holding off a challenge from Japan's Masata Sakai to win the men's 200-metre butterfly, and later returned to win his 21st gold in the 4x200m freestyle relay.

Phelps is the most decorated Olympic athlete in history and built on his legend in Rio with a dramatic victory over Sakai and Hungary's Tamas Kenderesi. Just over an hour later - and with a medal ceremony in between - he anchored the United States in a convincing relay win over Britain and Japan.

In another thrilling race over 200m, American teenager Katie Ledecky won thefreestyle to maintain her bid to match Debbie Meyer's 1968 record of sweeping the discipline in 200m, 400m and 800m. Ledecky already has the 400m title and is strongly favoured to add the 800m crown on Friday.

And Hungary's Katinka Hosszu also expanded her collection of Rio gold with victory in the women's 200m individual medley.

But there was no doubt the night belonged to the 31-year-old Phelps and not only because he became the oldest man to win an individual swimming title at the Games.

The butterfly specialist was out to regain the title he won in 2004 and 2008 before losing on the touch to Chad le Clos four years ago in London after leading from the 50m turn.

"I was pretty fired up after that race," he said his delighted celebrations. "This is the race I really wanted tonight. I really wanted that one back.

"That last 10 metres were not fun. Oh my gosh, I thought I was standing still."

Phelps couldn't quite shake his pursuers though and, after Le Clos faded, Sakai threatened in the closing metres to draw level or even overtake him. This time there was to be no repeat of 2012 and Phelps won by four hundredths in 1 minute 53.36 seconds. Le Clos finished out of the medals in fourth as bronze went to Tamas Kenderesi of Hungary.

While Phelps is likely approaching the end of his legendary career, moments earlier compatriot Ledecky had taken another step of her own towards greatness.

She won in 1:53.73 for her second gold of the Games, and third overall, over Sweden's Sarah Sjostrom, who was herself chasing her second gold in Rio. Ledecky has never lost an international individual final and, despite losing to Sjostrom in the semi-finals, was comfortable in winning by 0.35 seconds.

"It was a really tough race but a lot of fun," Ledecky said. "It's amazing to get another medal.

"Once I hit the water I was on auto-control. I got in the lead and wasn't about to let it go."

World record holder Federica Pellegrini missed out on the medals as Australian Emma McKeon snatched the bronze.

The final individual medal went to Iron Lady Hosszu, who dominated from the first leg and was never in danger of not adding to the 100m backstroke and 400m medley titles won earlier in the week. She finished in an Olympic record of 2 minutes 6.58 seconds.

"I'm so excited to get the gold, I can't even believe it," Hosszu said. "I can't believe I have three golds."

Britain's Siobhan-Marie O'Connor was second, three tenths of a second behind, while bronze went to American Maya Dirado.

The session ended with Phelps returning to anchor the US relay team to a simple victory, which brought him his 25th overall Olympic medal.

Conor Dwyer, Townley Haas and Ryan Lochte had laid the foundation for the victory by handing Phelps a lead of well over a second for the final leg and he saw out the win in 7 minutes 0.66 seconds.

"Doing a double like that is a lot harder than it once was," he joked.

Britain took silver more than two seconds back, with bronze going to Japan.

In the semi-finals, reigning champion Nathan Adrian of the US progressed easily in first after claiming the final qualifying spot in the afternoon heats. Marcelo Chierighini of Brazil delighted the home crowd by sneaking into the final in eighth.

Australian Madeline Groves topped the women's 200m butterfly and in the men's 200m breaststroke Japan's Ippei Watanabe topped the sheets, having set a new Olympic record.

Latest news

Syrian opposition rules out future role for President al-Assad

The Syrian opposition said Friday it would not accept any role for President Bashar al-Assad in the future of the war-torn country, reacting to a recent US shift saying that removing al-Assad is no longer a priority for Washington.

Russian Army integrates breakaway forces of Georgian province

Parts of the small fighting forces of the Georgian breakaway province of South Ossetia have been placed under Russian military control, Russian Defence Minister Sergei Shoigu said on Friday.

Czech Republic's Pilsner Urquell beer is now Japanese

Japanese brewing company Asahi completed its takeover of the Czech brewery Pilsner Urquell on Friday, Asahi said in a statement.

Judge approves 25-million-dollar settlement of Trump University case

A US district judge on Friday approved a 25-million-dollar settlement of lawsuits and state fraud allegations against Trump University, the US president's now-defunct business venture.

Former Thai premier Thaksin to junta on reconciliation: 'Cut me out'

Former Thai prime minister Thaksin Shinawatra on Friday announced that he is not interested in the junta-led reconciliation process, three days after the junta handed him a half-a-billion-dollar tax bill for his past business deal.

Dalic: We welcome possible deal between Agrokor and banks

The government welcomes the possibility of an agreement being concluded between the Agrokor food company and creditor banks, and the bill on vitally important companies is not a fallback plan but the result of the government's care for the overall economic and financial stability of Croatia, Deputy Prime Minister and Minister of Economy Martina Dalic told a press conference in Zagreb on Friday.

Croatia, China sign action plan for cooperation in agriculture

The Croatian and Chinese ministries of agriculture on Friday signed an action plan for cooperation in the field of agriculture for the period 2017-2018, the Croatian ministry said in a statement.

ZSE indices up, Agrokor shares in focus of investor interest

The Zagreb Stock Exchange (ZSE) indices on Friday rose by more than 1.8%, with stocks of the Agrokor food and retail concern being in the focus of investor interest again.

Berlin police defend handling of Berlin market attacker

Berlin police defended themselves on Friday against accusations that they stopped surveillance on Berlin Christmas market attacker despite knowing in June 2016 he was dangerous.

Croatia, creditors tailor emergency measures to save tottering giant

Croatia's tottering retail and food giant Agrokor reached an agreement with its creditors, putting its debts standby and allowing it to continue working during emergency restructuring, the Croatian branch of Austria's Erste Bank said Friday.

Agrokor's creditors say standstill agreement to go into force today

A standstill agreement regarding the Agrokor concern's existing financial obligations to banks will take effect on Friday, additional capital will be injected into the concern in the coming days and the concern will be actively restructured, which includes a change of its management, it was said on Friday after a meeting between Agrokor's suppliers and creditor banks.

Palestinians, UN slam Israel's new settlement plan

Palestinians, Israeli activists and the UN lambasted the government of Israeli Prime Minister Benjamin Netanyahu on Friday, a day after it gave the go-ahead for the first new West Bank settlement in a quarter of a century.

South Sudan rebels release three abducted foreign oil workers

South Sudanese rebels have released three foreign engineers they abducted in early March in the oil-rich Upper Nile region, Foreign Affairs Ministry official Mawein Makol Arik said on Friday.

Turkish opposition: Imprisoned party chief has gone on hunger strike

The head of Turkey's pro-Kurdish opposition party has launched a hunger strike from prison.

European leagues threaten Champions League schedule clashes

The European Professional Football Leagues (EPFL) on Friday threatened schedule clashes on Champions League matchdays in an ongoing dispute with the governing body UEFA.

Danish court revokes citizenship of IS volunteer

A Danish appellate court on Friday stripped a man of his Danish citizenship for volunteering to fight for the extremist Islamic State in Syria.

Banks and Agrokor agree on key elements of standstill agreement

Member banks of the coordinating committee of financial creditors and representatives of the Agrokor food company have in principle agreed on key elements of a standstill agreement, which is expected to be signed later today, announcing changes in the company's management team, Erste Bank said in a statement on Friday afternoon.

Syrian man on trial in Sweden; mosque attack labelled terrorism

A Syrian man went on trial Friday in the southern Swedish city of Malmo, charged with terrorism and arson after an attack last year on a building used as an assembly hall by Shiite Muslims.