The Sunshine Tour, who co-sanction the tournament along with the European and Asian tours, posted a photo on social media on Wednesday of Oosthuizen's bruised and swollen fingers. "So when it rained all Tuesday at Randpark, I chose to use the trick".
140 was taking on the tougher Firethorn Course today but the big hitter thrived on the lengthier of the two layouts which was playing even longer due to heavy rain.
"Obviously, I am very happy".
The Joburg Open remains the only South African tournament serving as an official qualifier for The Open Championship in the United Kingdom and the stakes could not be higher to clinch the title.
The tournament at Randpark Golf Club starting on Thursday, was set to feature SA's top-ranked player, at 23rd in the world, but a freak incident left Oosthuizen with no choice but to withdraw.
The two-time European Tour victor kept a bogey off his card and made three straight birdies on the front nine before picking up four shots in six holes after the turn to vault into the share of second place.
Six golfers lie second on 64 - South Africans Jared Harvey, Erik van Rooyen and Ockie Strydom, English pair Matthew Baldwin and James Morrison and German Sebastian Heisele.
"I was really looking forward to playing in the Joburg Open for the first time so I'm very frustrated".
He had a disappointing day, making just four birdies to go with three bogeys for a one-under 70 on the Bushwillow course.
"When I played at Simola (recently) my little boy was sick with a bad chest, then my wife had the flu and then I got the flu, and lost a lot of weight". South African Darren Fichardt is the defending champ.
Title favourite and former British Open victor Louis Oosthuizen of South Africa withdrew after a freak eve-of-tournament accident.
American Cody Martin took his place and returned a 71.