The two Ryder Cup stars shot matching six-under-par 66s to sprint three strokes clear of their nearest rivals on 17-under 199 and will engage in a head-to-head showdown for the $1.33-million first prize on Sunday.
A rock-solid Donald took his outstanding record in the tournament to 100 holes without dropping a stroke while the big-hitting McIlroy was boosted by an inspired birdie-birdie-par-eagle burst from the 11th.
South African compatriots and close friends Louis Oosthuizen (68) and Charl Schwartzel (67) were in a tie for third place on 202.
There has been a sense of anti-climax all week at the final event of the European Tour season with McIlroy having already secured the money-list titles on both sides of the Atlantic.
Billboards in the city have dubbed the tournament 'The Greatest Show on Earth' and, while that description is overdoing the hyperbole, the top two players in the world will be looking to put on a dazzling exhibition on Sunday.
"I think everybody is looking forward to the duel between the number one and two tomorrow," said Northern Irishman McIlroy who is chasing his fifth victory of the year.
"I know I'm excited. It will be a great way to finish the season."
Asked by reporters whether he was concerned about Donald's remarkable run at the Greg Norman-designed Earth course, the 23-year-old McIlroy replied: "If you look at it logically it means he's due a bogey.
"I've not had that many battles with Luke down the years - that's probably because the courses we do well on are different. He excels on the shorter, tighter ones and I guess I play better on the longer courses."
McIlroy suffered from sunstroke earlier in the week and was again under the weather on Friday night.
"I was up at about four o'clock and had a bit of a fever," he said. "But I had a good warm-up this morning and struck the ball really well on the practice range.
"The heat here probably helps a little bit and the adrenaline of being in contention gets you through."
Donald is pinching himself at the thought of going 100 holes this year and last in Dubai without carding a bogey.
"That's a little hard to fathom even for myself," said the 34-year-old Englishman who finished third here in 2011 to become the first player to win the money-lists on both sides of the Atlantic.
"I bet my next run is not even close to that, probably something like 40 or 50 holes. I remember this time last year I was again just trying to play solid golf and minimise mistakes.
"It's a testament to how I play the game. I kind of keep the ball in front of me and when I do get in trouble I've got a good short game to bail myself out."
Donald, who is gunning for his fourth win of the year, knows he will be repeatedly outdriven by his Ryder Cup team mate in the final round.
"My game is different to Rory's," he said. "He is a power player and I can't go out and try to hit the ball harder or anything like that.
"I just have to play my own game. It will be a fun end to the season."
The round of the day on Saturday belonged to Jeev Milkha Singh who dedicated a sparkling 64 to his ailing 76-year-old mother back home in India after equalling the course record to finish on 209.
Singh, who became the first Indian to play in the Masters five years ago, said his mother Nirmal was in intensive care in Chandigarh after having a bad fall in the garden.
His round matched the record held by Britons Lee Westwood and Ross Fisher, Peter Hanson of Sweden, German Martin Kaymer and Sergio Garcia and his fellow Spaniard Alvaro Quiros who won last year's edition of the Dubai tournament.
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