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Geary, who tied for second at last weekend's New Zealand Open at The Hills in Arrowtown, topped the leaderboard following the morning round with a score of 9-under-par 63.
The Mt Maunganui pro now holds the Pegasus Golf and Sports Club course record and a two-shot lead over the field.
"I hit the ball nicely all day and gave myself lots of good looks," he said.
"I got off to a good start. I was 5-under through nine holes I made a nice eagle on the par-5 early to kick start my round a bit.
"Then I birdied the ninth hole turning at 5-under and then missed a couple of opportunities on the front nine but was able to make some nice putts on holes six and seven.
"On the last hole there I knocked it on for a chance at eagle but couldn't quite convert."
Despite posting the low score Geary was not fully satisfied with his round.
"Believe it or not I missed some makeable putts but made some bigger ones so it evened out, but it felt a bit weird. I made some good big ones but couldn't really make the mid-range ones, but I'm happy with the way I hit it.
"My game was really solid, especially when the wind got up. Those last nine holes were quite tough in that wind."
A southeasterly picked up as the round progressed.
"I would say it would be pretty tough to play all 18 holes in that breeze," Geary said before the afternoon-round tee off.
"The greens are starting to dry out, too, which makes it tougher to get at some flags but obviously the scoring still could be good."
Conditions are expected to remain much the same for the second round in which Geary will again join Australians Matt Millar and Ben Eccles in the afternoon.
"If we get a windy draw, it could be quite tough but if it's calm, it could be easier . . .
Geary believed playing with equally high-calibre players increased his chances of success.
"It was great. They're a couple of great guys that I know pretty well," he said.
"They played really well, too. I just made a few more putts than they did but that was the end result."
Australian Jack Weston is off to a flying start in his first tournament as a professional, sitting alone in second place, two shots off the lead.
Queenstown's James Antiss hit a 2-under 70, while fellow Queenstown golfer Fraser MacLachan finished 2-over.
Ben Campbell is not playing because of injury.
Michael Campbell had a round to forget, hitting a 6-over-par 78 and is unlikely to make the cut today.