France's Tony Yoka earned a nervy split-points decision to win super-heavyweight gold at the Rio Games on Sunday and add to the Olympic title won by his fiancee.

Yoka's triumph over Joe Joyce of Britain means it is a double celebration after his fiancee Estelle Mossely won France's first women's Olympic boxing crown on Friday.

The couple embraced ringside after he got the narrow win before wrapping themselves in a French flag, as boos from the crowd greeted the judges' verdict.

"I thought the gold was mine, I'll just have to watch it again. I was landing shots on him and getting through his guard. He nicked it," Joyce, 30, a fine arts graduate, told the BBC.

"I gave it my all, got the training right, just disappointed. Silver isn't that bad but I expected the gold -- it just wasn't to be."

Anthony Joshua, the British heavyweight champion watching ringside and a gold medallist at London 2012, said Joyce deserved the win.

"I've never seen a heavyweight throw so many punches in a fight. For me he is the Olympic champion in spirit. The sky is the limit for him. He is a credit inside and outside the ring.

"I was just praying he would catch him with one punch. The power Joe possesses... he is a phenomenal fighter."

Joyce made the better start, landing some clumping punches to rock the Frenchman.

Yoka was more mobile but Joyce was packing the greater power in the final bout of the boxing tournament in Brazil.

The 24-year-old Yoka seemed sluggish and unable to get his punches away, with Joyce working the body frequently.

The pair were gasping by the third and final round, with Mossely watching anxiously on from the stands. 

A confident Yoka stuck his tongue out at the Briton seconds from the final bell -- confident he had the decision.