Els, who shot an even-par 71 in the first round, had an eagle and five birdies on the 7,169-yard Serapong course. He credited his performance with better putting on the greens.
'My putting was the main difference today. I made some more putts,' the South African said. 'I hit some putts yesterday after the round and kind of found a little secret and went with that today.'
Strange, who won this year's Philippine Open, shot a 69 for a two-round total of 6-under 136.
Former U.S. Open winner Michael Campbell of New Zealand had four bogeys and a double bogey for a disappointing 75, leaving him five strokes off the lead.
Defending champion Adam Scott shot a 69 and is three strokes off the pace.
'I'm definitely striking the ball well enough. I just need to get my share of putts over the weekend,' Scott said.
England's Lee Westwood also had a 69 to remain in contention with a two-day, even-par total of 142. Ryder Cup teammate Paul McGinley of Ireland failed to make the cut after his 77 put him at 11-over 153.
The cut was set at 6-over 148.
Argentina's Angel Cabrera (68) was a stroke off the lead in third place, one shot ahead of Japan's Shingo Katayama (69) and Australia's Brad Kennedy of (67).
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