William Fox-Pitt admitted he couldn’t have asked any more of his horse Chilli Morning after the pair conquered a tricky cross-country course to take command at the World Equestrian Games in Normandy.
World number one Fox-Pitt finished the course with a score of 50.3 and narrowly leads Germany's Sandra Auffarth.
Four riders are within four penalties of Fox-Pitt's total, meaning just one fence down for the Briton on Sunday will open up an exceptionally close contest.
"He was strong. He's a feisty and opinionated horse," said Fox-Pitt after recording the day's fifth-fastest round, adding to their second-place performance in the opening dressage phase.
"He's never been asked these questions before or over such a demanding track and ground, but he was amazing."
While Fox-Pitt sits pretty atop the standings Great Britain are second in the team event after a German penalty was wiped out.
Former world champion Zara Phillips, the first Briton out onto the course aboard High Kingdom, set the tone for her team with a clear ride and 14.4 time penalties on a day when nobody rode inside the designated optimum time.
"It was tough out there but High Kingdom was a total star," said Phillips, 33, who won individual gold in 2006 and now lies 15th. "He was in control and I just steered."
Nicola Wilson and Annie Clover (12th) and Tina Cook with De Novo News (14th) ensured Britain finished the day with four riders inside the top 15, with Oliver Townend and Black Tie the only British combination not to finish.
However the day was tinged with disappointment as horse Wild Lone, ridden by Fox-Pitt's team-mate and son of three-time Olympic champion Richard Meade Harry Meade, collapsed and died after Saturday's competition.
© Sportsbeat 2014