Henrik Stenson fired a seven-under-par 65 to take a commanding lead at the SA Open Championship before thunderstorms stopped play as Australian Daniel Gaunt found the going tough on Friday. The Swede moved to 13-under at the Serengeti Golf & Wildlife Estate to lead countryman Magnus Carlsson and overnight leader Merrick Bremner by four strokes. Playing in calm early conditions, Stenson posted five birdies and an eagle by the par-five eighth to maintain his buffer at the top of the leaderboard. Bremner managed just 14 holes before thunder and lightning rendered the course unplayable. Scot Lloyd Saltman shot a 66 to move to outright second at eight-under while South Africans Oliver Bekker and Matthew Carvell, and Swede Michael Jonzon, share equal fifth at seven-under. US Masters winner Charl Schwartzel was two-under through 14 holes, leaving him tied for eighth at six-under overall. Australian Gaunt is at two-over overall after a 74 following his even-par 72 on Thursday and is in danger of missing the cut.