The 55-year-old began with a birdie on his opening hole, then hit three in a row on holes 5-7. The last half of his round featured additional birdies on the 10th, 12th and 15th as he went bogey-free in surging ahead of closest pursuer Retief Goosen.
His fellow countryman Goosen had higher highs and lower lows in Sioux Falls, South Dakota and he did it on back-to-back holes. Following a bogey on the par-4 11th, Goosen rallied immediately for an eagle on the par-5 12th.
Goosen also had four birdies to get to 10 under for the tournament.
Sitting third at nine under is American Bo Van Pelt, who like Goosen shot a five-under 65 on Saturday.
Spain's Miguel Angel Jimenez (65) sits alone in fourth at eight under.
Tied in fifth, four shots behind Els, are Demark's Soren Kjeldsen (65) and Argentina's Angel Cabrera (69). Cabrera had posted a bogey-free, six-under 64 to take the Friday lead.
All 11 Aussies are out of the running with Steve Allan (70) and Mark Hensby (68) leading the way at two under.
Greg Chalmers (72), Matthew Goggin (67) and Richard Green (69) sit a further shot back, while Stuart Appleby (71), John Senden (72) and Michael Wright (68) are even.
Rod Pampling (72), David Bransdon (67) and Brad Jones (76) are all over the card.
With AAP.
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