Zhang Xi (left) from China spikes a ball past Anastasia Vasina from Russia during their beach volleyball match on Saturday. Zhang and her partner Xue Chen lost 18-21, 21-14, 16-14. Petr David Josek / Associated Press

Bikini-clad women served up a shocker in more ways than one outside the back window of British Prime Minister David Cameron to open London Olympic beach volleyball competition on Saturday.

Horse Guards Parade, a venerable park area dating to 1745 where the Queen's pageantry-filled official birthday party is staged, had nearly 15,000 people packing temporary stands for a spectacle on sand unlike any other.

"You guys are at the most iconic venue," stadium announcer Mark Perkins told the crowd as he encouraged cheers. "Let Mr Cameron hear you.

"Beach volleyball at Horse Guards Parade - who would have thought it?"

And in the first match, 2008 Olympic bronze medalists Xue Chen and Zhang Xi of China, ranked second in the world, were upset by Russia's Anastasia Vasina and Anna Vozakova 18-21, 21-14, 16-14.

"The crowd was exciting and during the first match, I think, we were a little bit nervous," Xue said. "The atmosphere was perfect. We are really enjoying London. We just need to focus. We made too many mistakes. It was more mental."

Whitehall government office buildings loomed in the background along with Cameron's residence at No 10 Downing Street and the top half of the London Eye Ferris wheel.

Buckingham Palace, Big Ben, the Houses of Parliament and Westminster Abbey were just down the road.

"Maybe the queen heard you then," Perkins enthused after a loud cheer from the crowd.

At the heart of it all were 4,115 tons of quarry sand brought from Surrey in 3,483 truckloads where players could spike, dig and smash in quest of gold under sunny skies and cool breezes that could pass for California oceanside.

Matches are played from early morning to midnight, four to a session, with two each of men's and women's volleyball providing something for everyone to enjoy with every ticket.

Sand grains still clung to the players after the match as they talked about an atmosphere that was so fun it was unnerving at the start.

"There were so many people watching us," Vasina said. "In the beginning we were a little bit nervous and excited about it. That's why we lost the first set. The crowd was good. A lot of people were supporting us."

Vasina only laughed and smiled when asked if she hoped Cameron had been watching.

The Russians won the final four points of the match, saving two match points on Vasina blocks and then winning on another Vasina block and a spike by Vozakova.

"The Russians played really great," Zhang said. "There has been a lot of pressure on us and we made a lot of mistakes. We need to focus ourselves and we will be better prepared. We won't look back on this match."

The chimes of Big Ben rang in the background as the first point began, a block by Xue landing just inside the sideline for a winner by the Chinese duo.

There were no hooligans, no segregated stands for away team supporters - just families and friends cheering on sports for sports' sake at the largest venue in Olympic beach volleyball history.

Music from the Beach Boys and peppy dance tunes dominated the moments between the points, including We Will Rock You and Benny Hill theme music, as rakers smoothed over the footprint-filled playing surface during timeouts.