Their challenge this weekend is to overcome Yardley's 108 point advantage going into the Grand Prix weekend.
Te Puke's Michael Scott is closest to Yardley - and would be closer if not for a catastrophic crash at the opening round that threatened to sideline his campaign. With the support of friends and donors on a Givealittle page, Scott was back at the next round and has shown the value of consistency, with three second placings delivering him into second place. Scott was Yardley's team-mate in last year's championship.
Reid Harker dropped to third after a fraught fourth round at Teretonga near Invercargill; but remains just eight points behind Michael Scott.
Ryan says with a possibility of rain at the weekend, the weather influence the racing but all three have shown they are capable of top results even in the chill sleet encountered at Teretonga, and if there is rain the Michelin wet tyres available to the championship when things turn slippery offer "world-class" grip.
Jack Milligan, fourth overall, has his own battle to pay attention to. He is the leading rookie, but right behind him is the fast-improving Brody McConkey in the striking Castrol-liveried Albany Toyota TR 86. Milligan won a race at Teretonga, his first outright victory in the championship.
The 2016-2017 Toyota 86 Championship is the richest race category in the summer series, with a prize purse across all six rounds of $100,000. It is open to a race version of Toyota's acclaimed 86 sports coupe, the TR 86. Built in Toyota's Mt Wellington race headquarters, the cars feature an FIA-specification roll cage, touring car race seats and harnesses, a full race brake package and adjustable suspension. They run on Michelin slick tyres with a wet tyre option.
There are three races this weekend for the TR 86 field; three chances to score 75 points by winning a race. The championship winner may well be found right here this weekend.
Yardley could put the title out of reach of his rivals, or with a slip could allow Scott or Harker to close in and even overtake him.
Championship points
18Ryan Yardley 744
5Michael Scott 636
4Reid Harker 632
17Jack Milligan 553
23Brody McConkey 520
3John Penny 475