The amateur prospect from Ballymena, Northern Ireland, showed his liking for the 6,703 metre layout at Benoni Country Club as he reeled in eight birdies – including two sets of three – and dropped just a single shot to produce a sizzling 65 and take the lead at 10-under-par 134.
McElroy said Myende caught his bag after his regular pro, Mikhail Tewary, crashed out of the Joburg Open qualifier.
“Mikhail’s loss is my good fortune,” the 20-year-old 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.”
The Irishman will join Bradley Neil from Scotland and South Africa’s Stefan Cronje in the final match, on Thursday, after the Scotsman fired a 66 and Nigel’s Cronje a 67 to get to eight under.
South Africa’s Jason Smith and Paul Elissalde from France also took route 66 to finish three shots back, while the Swiss pair of Joel Girrbach (70) and Edouard Amacher (65) are tied a further stroke back on six under with overnight leader Christiaan Bezuidenhout.
The local favourite had to draw on all his powers of recovery to eliminate five bogeys for a 74, but McElroy is certain the SA number one will be close to the top at the end of round three.
“I played with Christiaan in the final match at the Free State Stroke Play for 36 holes, so I had a front row seat to his victory,” McElroy said.
“He is an incredibly talented player, and one bad round means nothing. He will fight his way back to the top.”
This is the second successive year that McElroy has come out to South Africa with a squad from the Golfing Union of Ireland to play the SA Stroke Play, and he arrived determined to improve on his tie for fifth at Oubaai last year.
“I took a lot of confidence from the top five finish at the Free State last week,” he said.
“I really enjoy playing this course. The layout suits my game and I’m enjoying the altitude. It’s just crazy just how far the ball goes up here.
“The ball really flies up here, too. At the last hole I had 240 yards to the flag, and that’s normally a 3-wood for me and here I’m hitting three-iron.”