John Nicholson designed a course that clearly sorted the seasoned from the inexperienced in the Rush Munro's CIC3* at the Hawke's Bay Equestrian Park.
Wigley, who was second overnight, rode NRM Frog Rock inside the optimum time to move into the lead on their dressage score of 53.3, with Simon Gordon (Auckland) and Fletch.com moving up from fifth to be second on 55.4, also without incurring any time penalties.
Abby Lawrence (Te Puke) and Pseudonym added 0.4 time penalties to their sixth-place dressage score to climb to third on 56.4, while Wigley was also inside the time on her second ride NRM Enzo moving up from eighth to fourth on their dressage score of 56.9.
All but one of the 17 starters in the top division completed the course, with only one incurring jumping penalties, but Wigley on both her horses, and Gordon were the only ones inside the optimum time.
Overnight leader Donna Smith (Te Kauwhata) incurred 14.4 time penalties with Balmoral Sensation, which saw them slip to eighth, while her third-placed ride Just Chocolate dropped out of contention with 21.2 time penalties.
Sunday morning's showjumping phase, which is jumped in reverse order of merit, will be very tense as less than four penalties - the cost of dropping just one rail - separates the first four competitors. All horses must pass the veterinary inspection before going forward to the final phase.
In showjumping, a single clear round by double Olympian Daniel Meech aboard Winston Darco V took the honours in the premier stakes, with Rachael Bentall (Hastings) on Kiwi Brave second with a time fault, and Catherine Cameron (Cambridge) third on Campione GNZ, also with a time fault.