Simpson carded a nine-under-par 63 to move to the top of the leaderboard, opening up a two-shot advantage over Kieron van Wyk and Louis Albertse.

He is now on 16-under-par 128, having opened with a 65 in the first round.

Going into the second round tied for sixth place and two shots off the lead, Simpson made a brilliant start, picking up birdies at the first and second holes before an eagle at the third. He then dropped a shot at the fourth but bounced back with three more birdies at the sixth, seventh and ninth to make the turn in 30.

On the back nine, he picked up further birdies at the 10th and 14th before dropping a shot at the 16th. He finished in style with an eagle at the 18th for an inward 33.

Van Wyk and Albertse are tied for second place on 14-under-par 130. Van Wyk carded a 66 in the second round after opening with a 64, while Albertse followed up his opening 65 with another round of 65.

Dean Burmester sits in fourth place on 13-under-par 131, followed by Kyle De Beer in fifth on 12-under-par 132 and Deon Germishuys in sixth on 11-under-par 133.