'I have been playing really well this week,' said Els. 'It is a good week. You don't change anything. You go ahead and play the golf course.'
Australia's Adam Scott battled valiantly, but in the end failed to make up any ground on the front-running Els. Scott posted a 68 of his own to join Gareth Paddison in a tie for second at 14-under-par 202.
The first two rounds on the Composite Course at Royal Melbourne were all about records for Els. He came close to 59 with a magical round of 60 on Thursday and established a 36-hole European Tour record for strokes under par after a bogey-free 66 on Friday. Now that the weekend had arrived, Els kept on plugging away unchallenged.
'You just want to go out there and play as good as you can and play your shots and not be afraid to play them,' said Els. 'A lead like this, it starts making you play too safe.'
Els knocked his second shot into a bunker at the par-5 second but blasted out of the sand to six feet for his first birdie of the day.
The South African found another bunker at the par-4 fifth but played his shot out of the sand inside three feet and converted the short birdie putt. He faltered with a bogey at the par-4 sixth after an errant drive but came right back with a birdie at the very next hole.
Els found trouble off the tee again en route to a bogey at the par-5 ninth to give Scott a glimmer of hope.
At the par-5 10th, Scott converted an eagle putt from off the green to briefly pull within four of the lead but Els answered back with an eagle of his own.
Els again pulled away with a magnificent birdie at the par-3 11th after his tee shot stopped within a few feet of the hole. He then moved eight strokes clear of the field with a 10-foot birdie putt at the par-4 12th.
He stumbled to a bogey at the par-4 16th, but his challengers had problems of their own coming home. Now with one round to play, the Big Easy owns a more than comfortable advantage as he tries to become the first player to win this event three straight times.
'I'll go out there and play my game tomorrow,' said Els. 'I want to keep going. I want to play better tomorrow. I feel that I can play better than I did today. I want to do that.'
Scott, who played alongside Els for the third straight day, opened with birdies on each of his first two holes.
At the par-4 seventh, Scott dropped his approach inside three feet for another birdie before his eagle at the 10th put him within striking distance of the lead.
Ultimately, Scott could not match Els down the stretch and he closed with a birdie and two bogeys over his last three holes.
'He still played well today but I felt like I had my chance to maybe sneak up to five back or something like that and I did not take it,' said Scott. 'He played very smart and he is still in total control.'
Peter Fowler carded a 3-under 69 to join fellow Australian Peter O'Malley and Peter Hanson of Sweden at 13-under-par 203. New Zealand's Mahal Pearce was one shot further back at 12-under-par 204.
Michael Campbell, twice a winner of this event, finished alongside Stephen Gallacher, Paul Sheehan and Peter Baker in a tie for eighth at 11-under-par 205.