Former England captain Ollie Phillips was world sevens player of the year in 2009

Former England captain Ollie Phillips has predicted that rugby sevens will provide "a cracking spectacle" at the Rio Olympics.

The Great Britain squads for men's and women's competitions are set to be announced in London on Tuesday.

And Phillips, who skippered England during a glittering sevens career that also saw him named 2009 world sevens player of the year, is relishing a six-day tournament which starts at Deodoro on August 6.

"It's brilliant that rugby is part of the greatest sporting spectacle on the planet, and that both our men and women get a chance to be a part of that," he told Press Association Sport.

"To win a gold medal, for most sportspeople, is the biggest accolade you can have.

"I think the Olympics will get a cracking spectacle. There is nothing, really, that exists within the Olympics whereby the action comes very thick and fast, and there is always something going on.

"Sevens is short, sharp, with loads of points and a carnival atmosphere."

GB's men and women have built for Rio by taking part in a series of preparation tournaments - the men triumphed on successive weekends in Exeter and Gdynia, Poland earlier this month - with final 12-player groups now ready for unveiling.

The men have been drawn alongside New Zealand, Kenya and Japan in Rio, with the women facing Canada, Brazil and Japan during pool stages that will see the top two teams from each of three groups - plus two best third-placed sides - securing quarter-final places.

Phillips' ex-England sevens colleague Simon Amor is head coach of the men's squad, and while injuries have ruled out two initial training squad members - Wasps scrum-half Joe Simpson and Welshman Luke Morgan - it is expected that Amor will be able to parade a powerful final contingent.

"What I like about Simon's (training squad) selection is that most of the players have been playing sevens all year for England, Scotland or Wales, so their fitness levels will be right up there," Phillips added.

"In sevens, there is an expectation for players to be supremely fit.

"A lot of it in sevens is just about the core skills that lots of people take for granted - your handling, passing, tackling and how accurate you are at the breakdown.

"Sevens puts a huge magnifying glass over the core components of anyone's game. There is no hiding. If you miss a tackle in 15-a-side, sometimes that can be recovered. In sevens, more often than not, it can't be."

Fifteen-a-side world stars like Bryan Habana and Quade Cooper failed in their attempts to secure respective Rio selection for South Africa and Australia, and while New Zealand's Sonny Bill Williams made the final cut, Phillips has underlined how big the switch to rugby's abbreviated version can be.

"If you look at someone like Sonny Bill Williams, he came into the sevens environment and it took him a good three tournaments to get used to the game in terms of what he was doing, how to play and what decisions to make," Phillips said.

"Players have almost become 'specialist sevens players'. There is a lot more focus on some players doing nothing but being out and out sevens now, and that has seen the game grow.

"It is a challenge going from 15s into sevens. You cover a lot more yardage, there is a lot more running. It is more about agility and speed. Also, the recognition of space.

"In 15s, there is less space and it is crowded with players, and on a sevens field, it is all about appreciation of space, knowing when to take the gap between you and the defence or when to hold on and push out wide.

"The HSBC World Sevens Series has grown from six tournaments to 10, and the actual game of sevens is really exploding. I think the Olympics will contribute massively to that."