SIR Mark Todd could make history as New Zealand's most successful Olympian if he claims an eventing medal in his eighth Games in Rio later today.

Todd, based at Badgerstown near Swindon, lay fourth in the individual eventing competition after a brutal day on the cross country course, with Australia's Christopher Burton leading on Santano II.

Germany's Michael Jung - the London 2012 individual gold medal winner - was second, with France's Astier Nicolas, who is based at Stockley near Calne, third followed by 60-year-old double Olympic champion Todd.

The oldest rider in the eventing competition, who competed in his first Olympic Games in 1984, Todd has two individual gold medals to his credit and a bronze, as well as a silver and two bronze team medals already.

He and his German-bred Leonidas II added just two time penalties to their dressage score to finish on 46 penalty points heading into today's final showjumping stage.

“I had instructions from the team to go safe and clear,” said Todd. “The horse was brilliant all the way around. The instructions were also to ride safe at the fence where Tim had the problem and I think that probably cost me those few seconds.

“I am over the moon to have finished and gone well. It is a 3* course with 4* technicality. The fences come at you thick and fast.

“He (Leonidas) is so brave and honest. The team needed me to get round. When you are travelling at 570 metres a minute, the fences come at you thick and fast.

"There is no room for error – the horses have to stay really focussed. It is a real riders course out there.”

Spearheaded by Todd, the Kiwis are just 4.5 penalty points off leaders Australia, with France 6.2 penalties behind in third in the team competition. which will also be decided later today.

Clarke Johnstone and Balmoral Sensation are in seventh equal and Marlborough-based Jonelle Price aboard Faerie Dianimo is 13th after also producing clear rounds.

Price's husband Tim went off as the trailblazer for New Zealand but was eliminated when his horse Ringwood Sky Boy slipped going round a corner and the two fell.

“It was a gracious fall if there is such a thing,” said Price. “It was on the side of a slope and the momentum just took us. It is a challenging course out there and you try and leave no stone unturned in the build-up... then you go and fall over.

“He was going brilliantly and felt so good. I thought ‘game on’. I felt he was the right horse to be sitting on this day. I am just so gutted.”

It meant Jonelle, last out for the New Zealanders, could afford few mistakes on Faerie Dianimo and they delivered to leave their team in contention.

“We were a bit of a glum old bunch last night wondering how we would dig ourselves out of our hole,” she said.

“The Olympics are a once in a lifetime opportunity. It is something you leave with nothing in the tank.

“We took the dressage pretty hard. None of us performed to our personal expectation, but we went out (on cross country) with a positive mindset.”

Lower Stanton St Quintin rider Kitty King had a refusal on Ceylor LAN, meaning that Great Britain lie a distant seventh overnight in the team competition.

Britain have won an Olympic eventing team medal at every Games since 1996, but they are currently a huge 91 penalties off bronze medal position.