Big-hitting Nienaber fired an eagle, eight birdies and two bogeys in an opening eight-under-par 63 to join compatriot Shaun Norris at the top of the leaderboard at Randpark Golf Club.

Scott Hend, the 47-year-old veteran who was Australia's lone challenger in the European Tour event's 156-man field, did not enjoy the best of starts as a two-over 73 left him alongside a whole host of players tied for 109th place.

American Johannes Veerman and Canada's Aaron Cockerill were a shot off the lead with rounds of 64, while Welshman Rhys Enoch and England's Richard McEvoy were part of a five-strong group on six-under.

"Eight-under is nice around any golf course and to do it here in the first round of the Joburg Open, being back home again, is great." – Wilco Nienaber

Nienaber, who won the 2019 South African Amateur Championship before turning professional last year, started his round on the back nine with a par on the 10th, but did not make another until reaching the turn.

After making a birdie on the 11th, Nienaber followed an eagle on the 12th with birdies on the 13th and 14th before dropping shots on the next two holes.

Birdies on the 17th and 18th took Nienaber to the turn in 31 and he parred the 1st and 2nd before picking up further shots on the 3rd and 4th, the latter coming after a tee shot of 401 metres on the downhill par-5.

There was more big hitting to come on Nienaber's final hole of the day, the 20-year-old driving the green on the 348-metre 9th to set up a closing birdie.

"Eight-under is nice around any golf course and to do it here in the first round of the Joburg Open, being back home again, is great," Nienaber said.

"I haven't played much in South Africa since I turned pro but it's been great to be home. I'm just looking forward to the next three days and the next two weeks after."