Ballymena's Dermot McElroy built on a sensational start — five birdies in his first six holes — to post a brilliant 65 and snatch the halfway in the South African Amateur Strokeplay Championship.
With tentative plans to turn professional after June's British Amateur, the world No 53 fired eight birdies and just one bogey to lead by two strokes on 10 under par from Scotland's Bradley Neil and South Africa's Stefan Cronje at Benoni County Club in Johannesburg.
Seven of the eight-strong Irish challenge made the two-over par cut for the top 70 and ties — Headfort's Rory McNamara shot 74 to miss by one — but McElroy was the star of the show as he posted the joint low round of the day.
And the 20-year old did it with the help of a tour caddie, who proved to be invaluable.
According to the South African Golf Association, regular Sunshine Tour caddie Njabulo Myende carried his bag after his regular pro, Mikhail Tewary, crashed out of the Joburg Open qualifier.
“Mikhail’s loss is my good fortune,” McElroy said. “I struck the ball extremely well and my short game was on form, too, but when you have a caddie that can even read the spike marks, you pretty much can’t go wrong.”
After a birdie four at the opening hole, he then rattled off five threes in row with a birdie at the second followed by a par at the third and another three birdies in a row from the fourth.
Remarkably, his seven under par round yielded a haul of just one birdie from Benoni's four par-fives.
Had he hit form around the turn it could have been an even more spectacular but after settling for par fives at the ninth and 10th, he followed a bogey at the 11th with another birdie hat-trick from the 12th.
Four closing pars were not what he would have wanted but having ended up disappointed to finish joint fifth in the Free State Amateur in Bloemfontein, he is clearly finding South Africa to his liking.
West Waterford's Gary Hurley is the next best of the Irish in joint ninth on five under after a four-birdie 70 with Moyola Park's Chris Selfridge slipping from second overnight to tied 12th after adding a 74 to his first round 66.
Portmarnock's Geoff Lenehan shot 70 to share 21st on three under with Naas' Jack Hume also shot 70 to lie two shots further back on one under.
Balbriggan's Robbie Cannon (75) and Mourne's Reeve Whitson (73) had to battle to make the two over par cut on the mark.
But there was no luck for West of Ireland champion McNamara who paid a high price for a bogey at the 17th as he added a 74 to his opening 73.