Olympic gold medallist Laura Collett ensured that Great Britain’s eventers made a flying start to their world title bid in Italy.
Collett, who helped Britain win a first Olympic eventing team gold for 49 years alongside Oliver Townend and Tom McEwen in Tokyo last summer, surged into an overnight lead aboard London 52.
A dressage score of 19.3 penalties was the best world championship mark for 20 years.
Her team-mate and reigning world individual champion Ros Canter lies fourth aboard Lordships Graffalo, with world number one Townend and Olympic individual silver medallist McEwen performing their dressage tests on Friday.
Cheshire-based Yasmin Ingham, who is competing at the worlds as an individual on her major championship debut, is in second place with Banzai du Loir.
Collett and London 52 won the prestigious Badminton Horse Trials earlier this year, continuing a rich vein of form.
“He is just a pleasure to ride. He got better and better in the test,” Collett said.
“I am well aware that I am sat on one of the very best horses in the world. People expect you to deliver, and he delivered.
“He has been on amazing form for the last two years. Fingers crossed, he stays that way.”
Britain are chasing a seventh world team crown, having arrived in Pratoni as defending champions and firm favourites, while five British riders have previously won the individual title – Canter, Zara Phillips, Ginny Leng, Lucinda Green and Mary Gordon-Watson.
