Round two of the series at Moonshine, near Porirua, in September was won by Buxton, with Whitaker and Parker completing the Gold Class podium that day.
Whitaker leads the Gold Class overall after two rounds, just two points ahead of Buxton and a further three points clear of Parker, but anything can happen in this most arduous of sports and talented riders such as Rotorua's Bradley Lauder or Napier rider Mackenzie Wiig could also be expected to feature this weekend.
This weekend's two-dayer in Hawke's Bay (at 435 Puketapu Rd, in Taradale, for day one and then at Tutira, for day two) could be pivotal in determining where the silverware ends up this season.
Two consecutive days of battling brutal terrain will surely test the nerves, strength and endurance of these elite dirt bike riders. There will be diversions in place for the Bronze class riders to avoid some of the worst obstacles and a natural terrain motocross section is also included, providing a high speed element into the equation.
"The series is really storming along," Motorcycling New Zealand enduro commissioner Justin Stevenson said.
"We are getting good rider numbers at these events and we typically expect more at the two-day events, so there should be a great turn-out this weekend.
"There is a big enduro-cross section, the largest in New Zealand, that will be a feature near the end of the day on Saturday and there's good spectator viewing for that. We are looking forward to a splendid weekend of entertainment."
Just as it did for last year's inaugural extreme series, the competition will again wrap up with another double-header weekend, at the two-day Nut Buster hard enduro at Oxford, near Christchurch, on November 15 and 16.
Only three of the four rounds of the Yamaha NZ Extreme Off-road Championship are to be counted, with riders to discard their one worst score from the three North Island rounds.