Yet things could have been even better for the 27-year-old from Oslo if he hadn't made a double-bogey at the last in his otherwise faultless 67 on Saturday's third round 'moving day'.
Reitan, who turned professional in 2018, is on course for a second victory on the European circuit after claiming a play-off win in Belgium's Soudal Open in May.
Reitan started up the 18th in his third round with a seven-shot advantage, but a wayward tee shot and a six on the par-four hole put a dent in his lead. It's given a littler more hope to his nearest pursuer, South Africa's Jayden Schaper, who's on 12 under.
Should Reitan complete his victory on Sunday, he will become the first Norwegian to claim 'Africa's Major'.
"I'm very disappointed with the finish on the 18th, but I guess a good double in the end," Reitan said.
"It's just clear evidence that if you don't hit it in the right spots, then you can get severely punished.
"But overall, good today. I got out of some tricky situations, I did that well. With the score today, I'm happy."
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