Cook is wary weather will play crucial role

Cook and her Great Britain eventing team-mates, who include Zara Phillips, hold third place in the team competition after dressage.

The British quintet are 7.9 penalties behind leaders and gold medal favourites Germany and 4.9 adrift of Australia, with Sweden and New Zealand tied for fourth.

Germany-based Japanese rider Yoshiaki Oiwa is the shock overnight individual leader on a score of 38.10. Italian Stefano Brecciaroli is second and 56-year-old New Zealander Mark Todd, who is chasing his third Olympic title, lies one place behind.

Mary King and Imperial Cavalier remain the highest-placed British combination in 12th. Cook and Miners Frolic are 14th, William Fox-Pitt (Lionheart) equal 17th, Phillips (High Kingdom) equal 24th and Northallerton’s Nicola Wilson (Opposition Buzz) equal 39th.

Cook was faced with torrential rain, thunder and a threat of lightning during her dressage test in the main arena at Greenwich Park yesterday.

She coped superbly with the elements, though, as her score of 42 penalties kept Britain firmly in the mix for medals.

Attention now turns to course designer Sue Benson’s 28-obstacle cross-country track through the hilly and twisting terrain of Greenwich Park, and it promises to have a considerable effect on where medals – team and individual – will end up.

“We just hope it doesn’t rain too much because it will be very slippery around those corners on the cross-country course,” she said.