Olympic spectators missed key moments at the equestrian event at Greenwich Park on Saturday when they were forced to join long queues after food stocks ran out.
A number of stalls ran out of supplies at lunchtime, leaving customers with long waits while vendors restocked at the south-east London site. Many spectactors had not brought food to the site because they thought would not be allowed to bring it in.
As a result, many missed British rider Mary King's electric performance as they struggled to get something to eat. King, 51, in her sixth Olympic Games, had to quieten the audience to keep her horse, Imperial Cavalier, calm. The 20,500 capacity venue holds an unusually large crowd for a British dressage event; even big events like Badminton attract only a few thousand.
Equestrian sport manager Tim Hadaway said his team would have a "thorough debrief" at the end of Saturday and address any issues that had come up, including the catering.
Debbie Pearce, 50, from Greenwich, said: "We've been queuing for more than an hour. My friend's vegetarian and there's nothing for her to eat. We were in another queue but when we got to the front, they had run out of food.
"Nobody's brought anything in because we didn't think you were allowed to. We've paid to come and see the event, not queue for food."
Marlies MacKichan, 54, from Tunbridge Wells in Kent, had given up trying to buy food. She said: "There's just not enough; it doesn't seem adequate what they have for the crowds. We don't know what this stall is selling because they're just making things ad hoc, whatever they can find."
Gordon Verity, 69, and his wife Jennifer, 65, from Hampshire, missed King because they were queuing. Verity said: "You have to accept you're going to have to queue." But his wife said: "We did want to see Mary King but she's gone now. Everybody left at the same time as the judges to have lunch. If we had realised we could have staggered it a bit."
Hadaway said that overall the first day at the venue had been good and that he would address any issues that were raised. "I think it's gone amazingly well. There's a lot of happy, smiling faces enjoying the spectacle."
Other Olympic spectators are bracing themselves for the return of yet more wet weather on Sunday with heavy showers forecast for central and east London, and hailstones also a possibility. Paul Mott, of the weather forecasting division of the Press Association, said: "There will be some showers around in the afternoon, and some of them look like being quite heavy.
"There could be some thunder and even hailstones. It's also going to be a fairly cold day compared to recent days, with highs of 20 degrees.
"It looks like we'll see a return to drier conditions on Monday."
Other Olympic venues are also forecast to have rain, with the Met Office predicting heavy showers at Wimbledon, where the tennis event is taking place, from around 1pm and lasting through the afternoon.
Elsewhere, the archery at Lord's and the fencing and judo at the ExCeL Centre will be affected by heavy rain in the afternoon, the Met Office said. Meanwhile the cycling event will experience some lighter rain.
The Met Office also forecast heavy rain from around 10am at Eton Dorney in Buckinghamshire, where the rowing competition is being held, and similar weather at the Lee Valley White Water Centre in Hertfordshire for the canoe slalom.