Britain ruled the Olympic waves on Friday, winning gold in the men's four and women's pair with army captain Heather Stanning and Helen Glover defending their 2012 title.

Also celebrating on day two of the rowing finals at the Rodrigo de Freitas Lagoon by Rio's Copacabana beach were France in the men's lightweight double sculls, and the Netherlands in the women's double sculls.

Glover and Stanning were first to strike for Britain. The pair who registered the first gold for the London 2012 hosts four years ago comfortably accounting for New Zealand and Denmark.

"This week's been an emotional week. I'm not a very emotional person, but I'm going to have to change that after this week," said Stanning.

They even went one better than Katherine Grainger, who became Britain's most decorated female Olympian 24 hours earlier when landing double sculls silver at 40 despite taking a two-year sabbatical between London and Rio.

Glover and Stanning led throughout to become the first female British rowers to retain their Olympic crown.

Less than half an hour later their teammates Alex Gregory, George Nash, Moe Sbihi and Constantine Louloudis won the men's coxless four.

The quartet prevailed at the expense of Australia and Italy for gold, Britain's fifth successive Olympic win in the event.

"You imagine how this is going to feel but you can't fully realise it until it happens," said Sbihi.

Teammate Gregory spared a thought for the vanquished Aussies.

"We're mates with them. That's one of the hard things about sport, we're all after the same thing, we're just doing a job. It's war out there and we feel bad for them."

French duo Jeremie Azou and Pierre Houin won the men's lightweight double sculls.

They crossed the line in 6min 30.7sec to beat brothers Paul and Gary O'Donovan, who delivered Ireland's first medal, and Norway's Kristoffer Brun and Are Strandli.

Ilse Paulis and Maalke Head of the Netherlands won the opening women's lightweight sculls race in 7:04.03. 

They came in ahead of Lindsay Jennerich and Patricia Obee of Canada and Huang Wenyi and Pan Feihong of China.

Source: AFP