The Scotsman is seeking his second European Tour title in a bit more than a month in Durban, South Africa, after also taking the Nelson Mandela Championship in December.
Jamieson's 68 Saturday enabled him to finish Round 3 at 15-under 201, good for a five-shot lead over Louis Oosthuizen, who had entered the day atop the leaderboard.
Oosthuizen's disappointing 2-over 74 left him in a three-way tie for second place with first-round leader Thongchai Jaidee (73) and Julien Quesne (67) at 10-under.
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