Oosthuizen on course for back-to-back wins in Johannesburg

Home favourite Louis Oosthuizen fired a bogey-free 64 to boost his hopes of back-to-back South African Open titles in Johannesburg.

The 2010 Open champion shot seven birdies to hold a one-shot advantage over England’s Marcus Armitage, who raced through the field with a stunning 62 taking him to 14 under.