South African Brown, who started in the afternoon, was only able to play 12 holes of his opening round after a delay of an hour and 45 minutes on Thursday morning because of thunder and lightning in the area.
But the 27-year-old rolled in seven birdies before play was suspended at 6.17 pm local time due to darkness to lead the way at seven under par.
He was one clear of compatriot Jayden Schaper, England’s Nathan Kimsey and Austrian Maximilian Steinlechner, who all shot 64s, and Angel Ayora, who was also on six under with three holes left to play when play was suspended for the day.
Since 1972, only two players have ever won three consecutive DP World Tour events: Sir Nick Faldo and the late, great Seve Ballesteros.
Casey Jarvis has a chance to join the duo with victory this week.#JoburgOpen pic.twitter.com/YP2hm9oB7F
— DP World Tour (@DPWorldTour) March 5, 2026
The 22-year-old Jarvis, who’s seeking to join Seve Ballesteros and Nick Faldo as the only golfers since 1972 ever to win three European tour events in succession after his victories at the Kenya and South African Opens, made a bright start at three under with three to play.
Australian Austin Bautista was also going along nicely at three under after 11 holes when his day ended early, while Jason Scrivener recorded three birdies and four bogeys in his one-over 71.
Friday’s forecast looks bleak, which could be a headache for tournament organisers and greenkeepers at Houghton Golf Course.