Piggy French made a strong start to the Barbury International Horse Trials in Wiltshire on her Olympics horse DHI Topper W.
All five of the British eventing team that will compete at London 2012 next month - French, William Fox-Pitt, Zara Phillips, Mary King and Tina Cook - are in action at Barbury over the next few days.
Leicestershire-based French is competing in Barbury's CIC two-star section, as are Fox-Pitt (Lionheart) and Phillips (High Kingdom), with King (Imperial Cavalier) and Cook (Miners Frolic) among the CIC three-star dressage starters on Friday.
Barbury is the final run-out for Britain's Olympic combinations before Greenwich Park, and French's dressage score of 40.8 penalties gave her a comfortable lead.
She won the Olympic Test event with Topper last summer, and French again set the standard among a 52-strong field that sees Fox-Pitt and Phillips featuring as late afternoon starters.
New Zealand Olympic hopeful Lucy Jackson, meanwhile, set the early three-star pace on Animator II, scoring 46.2 penalties, with two other Kiwi combinations - Andrew Nicholson (Quimbo) and Clarke Johnstone (Orient Express VI) - also in the top five.
New Zealand's eventing team for London is due to be announced after Barbury.