Johannes Veerman finished day one of the South African Open in stunning fashion to card the lowest round of his European Tour career and claim a one-shot lead.

The American - ranked 327th - has been in excellent shape early in the 2020 Race to Dubai, securing a pair of top-10 finishes, after battling to make it through the Qualifying School last year.

That form continued in Johannesburg as he carded a bogey-free 62 on Thursday on Randpark's Bushwillow Course, topping the leaderboard at nine under.

Heavy overnight rain contributed to a slightly slower start, but Veerman played the back nine in 29 with four straight birdies from the 15th.

"It was a good round of golf today," he said. "The course was set up to go low out there.

"The wind didn't blow hard, the rough isn't long and the greens were receptive, so there was a good number out there.

"I kept hitting a lot of good shots on the front nine but I didn't make as many putts as I did on the back nine. On the back nine, I made two long ones of 40-plus feet.

"I hit 17 greens today, so that's a lot of chances I had for birdie."

Veerman's nearest challengers were Nino Bertasio and JC Ritchie on eight under, and Branden Grace played the best Firethorn Course round of the day to join five others a further shot back.

There were four home hopefuls in the top nine, while defending champion Louis Oosthuizen had a share of 10th on six under.

The 37-year-old went bogey-free but lost momentum after three consecutive birdies ending at the 12th, playing each of the remaining holes at even par.