They call Jackson 'The Surgeon'.
It's the perfect handle for the Kiwi maestro of such a precision sport.
He's New Zealand's number one BC3 boccia player, and take him on at your peril.
Born with a high degree of physical impairment due to cerebral palsy, Jackson, like all BC3 classification players, uses a human assistant and a specialist piece of assistive equipment called a boccia ramp to compete.
The ramp allows people unable to throw or kick to direct a small leather ball towards a 'jack' in a court sport that combines all the precision of bowls and petanque.
Keeping their back to the play to avoid influencing the set-up of each ball, the assistant positions the ramp according to the player's instructions. Jackson carefully releases the ball from the top of the ramp.
"The assistant is just a tool," says Bruce Bycroft, Jackson's right-hand man in the sport for more than a decade.
"Greig does all the hard work."
The strategy play is on a par with chess.
Bycroft got hooked when his son took up boccia at 13.
"We used to play against Greig, and when my son moved onto other things I began helping Greig as I really enjoyed it.
" I wouldn't still be involved if it wasn't such a riveting game."
"[It's] addictive and a game that takes a power of concentration," says Jackson. "I like to be aggressive.
"Once I'm on the court, I'm not thinking about anything else apart from winning the game.
"It's the concentration that makes it physically tiring.
"Each game takes about an hour – there are four ends that normally take about 15 minutes each."
Before boccia, Jackson had never ventured beyond New Zealand, but since 2002, he's travelled to Korea, Hong Kong, Brazil, Canada, Japan, Australia and Portugal.
"I've made friends all round the world through boccia," he says.
"It's been very special for me to be able to travel the world meeting all these wonderful people."
But it has not been easy with incessant fundraising to get to key tournaments abroad.
Travelling through airport security and aboard planes in a 160kg wheelchair is a rigmarole in itself.
Meanwhile, Jackson's got his eyes firmly set on taking out this month's nationals in Wellington, and then he'll have the next World Championships in Dubai at the end of next year to aim for.
At 53, he's one of the sport's oldest players, but the beauty of boccia is it's a great leveller of external differences, a sport in which age is truly just a number, and men compete as equals with women.
It's a mind game – the proof lying in the number of able-bodied people who have had a go against Jackson, only to get trounced as he blocks off all their moves.
Currently he's ranked 47th in the world, but he's been as high as seventh.
