Until then, amateurs had a proud record at the Open, with 10 winners in 49 years.
Yesterday, 22-year-old Groom showed he had the touch to play a significant role in the Open in the next two days.
He bogeyed the first hole, regained that shot on the ninth, then turned on the style coming in, with birdies at 12 and 15 and an eagle three at the par-five 18th, which had the tees brought forward 40m yesterday to compensate for the gusty winds.
After leaving Barrenjoey High School in north Sydney at 16, Groom worked in a butcher's shop before taking up a part-time role at the Warringah Golf Club.
"Over the past few years it's been four days a week, then three, now two," he quipped.
He qualified at Waikanae last Monday and went two under in his practice round.
This is his first visit to Paraparaumu Beach, but he is no stranger to New Zealand.
He was undefeated at the Southern Cross Cup - involving Argentina, South Africa, Australia and NZ - at Wairakei last October.
His target this year is the Eisenhower Trophy, amateur golf's holy grail, in Malaysia in October.
Groom has played two Australian Opens - getting in as a qualifier, and making the cut as a 19-year-old, and missing the cut last year. This week's Open is his third professional tournament.
Amateur performances held special interest on the second day of the Open, and when the last trio finished yesterday, five had survived for the business end of the event.
The remarkable story of 13-year-old Jae An continues. The Rotorua schoolboy followed his opening-day par of 71 with a three-over 74 yesterday, good enough to squeeze into the top 60 and ties for the last two days.
The best of the New Zealand contingent are Remuera's Brad Heaven and Tim Wilkinson from Palmerston North, who are equal 28th at even par after carding respective rounds of 70 and 72.
Wellington's Richard Hislop got through at three over after an even par round yesterday.
Sam Hunt and Eddie Lee, widely rated as the best of New Zealand's young amateurs, missed out, both finishing seven over.
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