Brazil's golden boys have tangled past

In their heyday, Brazilians Emanuel Rego and Ricardo Santos were the most successful men's beach volleyball pair in the world, winning every available trophy including Olympic gold in Athens in 2004. At the London Games, they are rivals.

Both men have teamed up with younger players and the two new pairs are both strong contenders for medals, setting up an intriguing contest against a backdrop of tangled relationships going back more than a decade.

Emanuel, who at 39 is competing in his fifth Olympics, is playing with first-time Olympian Alison Cerutti. The pair have swept all before them since coming together three years ago and are world champions.

Ricardo, 37 and in his fourth Olympics, is playing with Olympic newcomer Pedro Cunha, 29. They have only been together for a year and have not made as dramatic an impact as Emanuel and Alison, but they have already won several trophies.

Both pairs have won all three of their pool matches to come top of their groups. The knockout phase begins on Friday.

So how do Emanuel and Ricardo feel about the prospect of playing against each other?

"I don't want to think about it," Emanuel told Reuters.

A sport played only in pairs and involving tactical decisions to be made in a split second, beach volleyball requires very strong chemistry between the players.

Emanuel described his relationship with Ricardo as similar to that of two very competitive siblings.

"He is my brother, but now we are not so close," he said. "We are both very competitive so we are focused on our teams."

Watching the two pairs in action on the sand in London, it is clear that both Emanuel and Ricardo have paired up with younger versions of each other.