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They are among at least 10 with serious hopes of claiming the position for the World Championships in Le Dorat, France, in the first week of July, headed next by Wairarapa shearer David Buick, the New Zealand UK Tour teammate of Stratford last year.
Friday's heats start the countdown to what may become shearing's greatest race for second place.
Other hopefuls include 2010 World and Golden Shears champion Cam Ferguson and 2006 Golden Shears champion Dion King, both also of Hawke's Bay, Te Kuiti shearer Mark Grainger, Manawatu gun Aaron Haynes, Southlanders Brett Roberts and Casey Bailey, and new national circuit champion Paerata Abraham, of Masterton.
All except Ferguson and King have won open finals this season.
Only six will qualify for Saturday night's final of 20 second-shear sheep each, the fastest time expected to be under 16 minutes.
But there is a further hopeful to overcome in the New Zealand title hunt.
The 2012 World champion, Whangamomona farmer Gavin Mutch, who in France will represent his native Scotland and who in 2015 became the only shearer from overseas to win the Golden Shears open title in Masterton.
About 200 shearers and woolhandlers will compete at the New Zealand Shears, with 12 major titles at stake from open class to novice, including the championships' first women's event, which will culminate with a final on Friday night.
Open-class shearers will target a treble of the Open, New Zealand Shears Circuit and North Island Shearer of the Year titles.
Meanwhile world championships hopefuls Pagan Karauria, of Alexandra, and Sheree Alabaster, of Taihape, will be among those chasing the open woolhandling title won by Alabaster eight times from 2004 to last year when she ended the three-year winning streak of 2012 and 2017 world champion Joel Henare.
Other events include an annual inter-island shearing and woolhandling match, and a shearing match between, a New Zealand Shears team and the Warrnambool show team from Australia.
Woolhandling will dominate the opening day tomorrow, including the junior and senior woolhandling finals, while a Speedshear will be held in the nearby Waitomo Club on Thursday night.