"USA, USA," chanted one section of the crowd. "USA, USA," chanted another.
Which seemed pretty pointless. It was like going to an Olympic final and cheering for the human beings, because both teams in the women's beach volleyball were from over the pond.
That didn't mean there wasn't an edge to it. You know what local rivalries are like: it probably meant there was more of an edge to it. They all hail from California, too. "These girls don't like each other," I was tipped off by one fan, who seemed to know her beach volleyball.
On one side of the net, in the red bikinis, we had the Amazonian Kerri Walsh Jennings, all six-foot-three of her, and Misty May-Treanor, the pairing who have won the last two Olympics. And on the other side of the net, in the white bikinis, were the challengers: Jennifer 'Jen' Kessy and April Ross, the 2009 world champions.
Everything about Olympic beach volleyball is incongruous, especially when played at Horse Guards Parade against the backdrop of some of London's architectural splendour. In the crowd, blokes in suits drinking bottles of official Olympic beer rub up against others in Hawaiian shirts and beach hats. The crowd seems overwhelmingly male. Funny, that.
It is difficult to imagine that Baron Pierre de Coubertin had beach volleyball in mind when he resurrected the Olympic Games in 1896
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There's a party atmosphere - "Let's have a parteeeeee," urges the stadium announcer, repeatedly - with loud music, dancers and general joviality. And then the teams appear and threaten to kill the mood, because they are deadly serious.
It seems that everyone has come for a bit of a laugh, except the players. Then again, they are professionals: May-Treanor, the 35-year old playing her final game here, has career earnings of over $2m, and the others are not far behind. And an Olympic medal is an Olympic medal, after all. It doesn't have an asterisk, indicating: 'This was only for beach volleyball.'
True, it is difficult to imagine that Baron Pierre de Coubertin had beach volleyball in mind when he resurrected the Olympic Games in 1896, but he might have approved of the setting. It has won universal praise, with Horse Guards Parade described by some as the world's finest beach volleyball court. What, better than Copacabana? Better than Venice Beach and Bondi Beach? Really?
The game gets underway and it's level pegging until 11-11, and then the defending champs begin to pull away. I'm no expert, but it seems to me that having a six-foot-three Amazonian at the net is a great advantage. Walsh Jennings just stands there, blocking or smashing, while May-Treanor scurries around the sand, flicking the ball back into the air for her partner to finish it off. The other pair do a lot of scurrying, but many of their efforts serve as reminders that sand is not a great surface for sport. Terra infirma. Even the dancers, who appear in the interludes, struggle.
The champions win the first set, 21-15. And the second follows a similar pattern: level until the champs pull away to 14-11, and it begins to look ominous for Kessy and Ross. There's a shaft of light at 14-18, when the champs serve long, but in the next point Walsh Jennings is at it again. The challengers retrieve, set it up, smash, but it's as though a wall has been erected on the other side of the net: Walsh Jennings gets in the way every time.
It ends with a damp squib, when Kessy's serve lands out, and Walsh Jennings and May-Treanor collapse to the sand, and their tears begin to flow into the sand.
Like May-Treonor, Kessy said she would retire before Rio, so in theory Walsh Jennings and Kessy could join forces - but although both teams were gracious towards the other, their body language afterwards didn't suggest that this is on the cards.
So, there's the beach volleyball, with the men's final on Thursday evening. There is a lingering argument about whether it should be in the Olympics. If we have the beach version of a sport that is already in the Games in its indoor form, why not swingball as well as tennis, or subbuteo as well as football?
A little more seriously, if it's about appealing to the youth audience that the IOC is so eager to engage (though all four women's beach volleyball finalists were in their 30s), then why not urban downhill mountain biking, or parkour? Both would be spectacular and thrilling.
It also seems a shame that the glamour of beach volleyball leaves indoor volleyball in the shade. And it doesn't help, in London, that the indoor game is out on a limb, at Earl's Court, in the cavernous exhibition centre. It's a venue that lacks the shiny newness of the Olympic Park, or the splendour of Horse Guards Parade; it's a little bit shabby, but the sport is brilliant.
And the indoor volleyball players are phenomenal athletes. The Goliaths on each side of the net combine great skill with extraordinary dexterity, stooping to reach low balls, stretching to smash high balls and sustaining long rallies -- much longer than their beach-dwelling cousins.
Still, Prince Harry was a fan of the beach volleyball, and returned for Wednesday's final. "We wore our bikinis for him," said the defeated Ross.