Mo Farah has won his fourth Olympic gold medal and becomes only the second man in history to retain both the 5,000m and 10,000m titles.

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The 33-year-old Londoner won the 5000m final at Rio 2016 on Saturday (20 August) night, adding to the 10,000m he won a week ago, to cement his place as Britain's most successful Olympic track and field athlete of all time.

"It's every athlete's dream but I can't believe it," Farah said afterwards. "Being away from my family for so long, I knew I had to do something for them. I just want to go home now and see my beautiful kids and hang my medals around their necks."

Farah jumps for joy after his historic win in Rio (Ian Walton/Getty Images)

Farah accelerated in the final bend and fended off a late challenge from the USA's Paul Kipkemoi Chelimo to win in 13 minutes and 3.30 seconds. It was Team GB's 65th medal in Rio, matching the nation's record haul at London 2012, and their 27th gold.

Kipkemoi Chelimo was subsequently disqualified, which moved Ethiopian Hagos Gebrhiwet in to the silver medal position and handing US runner Bernard Lagat a surprise bronze. 

The last man to win both distance races in consecutive Olympics was Finnish great Lasse Viren at the 1972 Munich and 1976 Montreal Games.

Semenya triumphs in 800m

Caster Semenya of South Africa won the 800m Olympic gold medal, fighting from behind to overtake Francine Niyonsaba of Burundi on the final bend before cruising home.

Semenya won in a South African national record 1:55.28, while Niyoinsaba was 1.21 seconds behind. Margaret Wambui of Kenya took bronze in 1:56.89.

"I dedicate this to my team," Semenya said. "They've done a fantastic job. It's a great feeling. Just fantastic. I couldn't believe it. Just fantastic."

Centrowitz takes gold at last

Matt Centrowitz of the USA ran from the front and held off Taoufik Makhloufi of Algeria at the line to win the gold medal in the men's 1500 meters, finishing in three minutes and 50 seconds exactly. Nick Willis of New Zealand took bronze.

Centrowitz won the silver medal at the 2013 world championships and took fourth at the 2012 London Games.

"There's nothing like it," Centrowitz said of his win on Saturday. "It doesn't compare to anything else I've won in my life."

Kenyan favorite Asbel Kiprop fell halfway and finished sixth.

USA women and men rule the track

Allyson Felix won a women's track record sixth Olympic gold medal, helping USA to victory in the 4x400m relay.

Felix, who also won gold in the 4x100m relay and silver in the 400m, ran the final leg of the race as the US won in 3:19.06. Courtney Okolo ran the first leg, followed by Natasha Hastings and Phyllis Francis. Jamaica took silver and Britain got bronze.

LaShawn Merritt anchored the US men's 4x400m team to win an Olympic gold medal and regain control of the event at the Games.

Four years after the Bahamas beat the Americans, they finished in 2:57.30 seconds. The Jamaicans brought the baton home 0.86 seconds later, with the Bahamas taking bronze in 2:58.49.

Maiden win for Rohler

Thomas Rohler of Germany won his first major title with his penultimate throw of 90.30m to clinch the Olympic javelin gold medal.

Behind him, Julius Yego of Kenya took silver with a throw of 88.24m, despite having to retire injured late in the competition. Defending champion Keshorn Walcott of Trinidad and Tobago took bronze with 85.38.

High jump glory for Spain

Ruth Beitia savours her moment (Photo: Getty Images/Alexander Hassenstein)

Spain's Ruth Beitia won her first major championship at 37, taking gold in the Olympic high jump with a leap of 1.97m.

Beitia took gold on a countback, beating Mirela Demireva of Bulgaria into second place while Blanka Vlasic of Croatia took bronze.

Chaunte Lowe, a perpetual contender without a global title, also cleared the same height as Beitia but fell just outside the medals.