A clear cross country, inside the time allowed, has moved New Zealand equestrian and defending Kentucky champion Andrew Nicholson up from 11th to seventh place at the American grand slam event.
Nicholson and 14-year-old horse Avebury were one of just 19 combinations of the 55 starters to remain on their dressage mark.
William Fox-Pitt (GBR) and Bay My Hero now leads the field on 44 penalty points, with overnight leader Alison Springer (United States) and Arthur slipping to 26th after picking up jump and time faults in the cross country.
All but one of the top 10 were clear and inside time, and of the 39 still in the field, 10 picked up jump faults. It seems the middle section of the course proved the most challenging.
Ten were eliminated, six retired and five withdrew before the cross country.
Sir Mark Todd and Oloa (owned by Di Brunsden, Peter Cattrell, Pip McCarroll and Todd) were one of those to withdraw.
Equestrian Sports New Zealand high performance coach Erik Duvander says the horse, who struggled in the dressage, would now probably be tilted towards Luhmuhlen, another of the top four star events.