Ashleigh McKinstry and Pioneer Brass Monkey leapt from tenth to sixth with the second fastest round, incurring 11.2 time penalties for a total score of 49.1.
So tomorrow's showjumping is going to be extremely tense, with fewer than 4 penalties, the cost of a rail down, separating the seven combinations behind Clarke and "Ritchie".
There was one withdrawal following mild colic, one retirement and one elimination following refusals, and one 50 penalty score for jumping outside the line of the flag.
The official video, placed at each fence likely to cause a problem, confirmed that. No disputes arose as the competitors were able to view the corner and "skinnies" on videotaped footage.
"Both horses were very good. The extra effort that was made to improve the grounds was very much appreciated, especially the road crossings that had consolidated with use. The overnight rain helped too, but it is twisty and turny, and was measured very tightly, so difficult to make the time," said Johnstone.
The CIC2* horses did not handle their challenges so well, with three eliminations, one of which was missing a compulsory passage.
Chanel Griffiths, who was lying third, fell when Astek Guardsman slipped turning in the premier arena early in the class. Kate Herdson was lucky not to be rolled on when Eon stumbled at the middle element of the first water.
Abby Lawrence leads on Anonymous after adding 7.2 time penalties to their second-placed dressage score for a total of 34.2.
Fleur Rohleder was the biggest climber, leaping from 10th place to second on The Alchemist after adding 9.2 time penalties, to finish the day on 44 penalties.
Dressage leaders Samantha Felton and Ricker Ridge Sooty GNZ incurred 19.6 time penalties for a total of 46.3 penalties.
The interim scores after the crosscountry today:
■ CIC3*: Clarke Johnstone (Matangi) Balmoral Sensation, 40.4; Amanda Pottinger (Havelock Nth) Just Kidding, 47.2; Clarke Johnstone (Wolf Whistle II) 48.1; Abby Lawrence (Te Puke) Charlton Yamani, 48.8; Nick Brooks (Cambridge) For Fame, 48.9; Ashleigh McKinstry (Taumarunui) Pioneer Brass Monkey, 49.1.
■ CIC2*: Abby Lawrence (Anonymous) 34.2; Fleur Rohleder (Hamilton) The Alchemist, 44; Samantha Felton (Matangi) Ricker Ridge Sooty GNZ, 46.3; Sophie Alexander (Auckland) World Famous, 48.8; Rebel Morrow (Australia) Balmoral Henton, 50.1; Isaac Twigg (Waipukurau) The Juggler, 50.6.