The Englishman produced the shot of the week so far to set up an eagle on the par five eighth in a 65 that moved him to 14 under, a shot clear of Italian Francesco Laporta and Austria's Bernd Wiesberger.
Wiesberger finished with three birdies in a 65 of his own as he looks to become the first player to win three different Rolex Series events and hold three Rolex Series trophies at the same time, while 2019 Road to Mallorca winner Laporta carded a 69.
Westwood ended a four year European Tour drought with an emotional victory at the 2018 Nedbank Golf Challenge hosted by Gary Player, and would take his tally to a remarkable 25 wins with a triumph in the desert.
He would also become the eighth man to win multiple Rolex Series events, joining countrymen Tommy Fleetwood, Tyrrell Hatton, Justin Rose and Danny Willett, Wiesberger, Swede Alex Noren and four time winner Jon Rahm.
"It's always a bonus to be in contention and that's basically why we come out here," said Westwood.
"I'm not going to lie, I didn't play a lot of golf coming into it, didn't know what to expect. To be in the lead with one round to go, it's a real positive.
"I'm just going to go out there and play as well as I can and if it's good enough, then great. I know I'm talented enough to win the tournament, it's just a case of applying myself."
Overnight leader Laporta dropped a shot on second and there was briefly a seven way tie at the top.
Westwood holed a ten footer on the third and then made a gutsy par save on the next before an excellent approach to the fifth saw him join the group at nine under.
In an almighty scrum on the leaderboard, the group at the top swelled to eight at one point, with over 40 players within three of the lead.
Westwood blew that all open with an incredible second at the par five eighth that took a bounce and rolled to within three feet for an eagle and two shot lead.
An approach to four feet at the ninth and a wonderful tee shot at the 12th moved the former World Number One to 13 under but Laporta and Wiesberger were both within striking distance.
After a birdie on the third, Wiesberger played an excellent tee shot at the seventh, put an approach to eight feet at the ninth and another to six feet at the 13th.
Laporta, meanwhile, bounced back from his early blemish by taking advantage of the eighth and leaving himself a tap-in at the par three 12th.
Westwood made a first bogey of the day after sending his second shot left on the 14th and when Wiesberger holed putts from inside 15 feet at the 16th and 17th, there was a share for the lead.
An excellent approach shot at the 16th edged Westwood back ahead but Wiesbeger recovered from a poor tee shot to birdie the last, with Westwood then making his own gain on the par five with two putts.
Laporta put an approach to tap-in range at the 16th and holed a 25 footer on the next but could not make the most of the 18th.
Fitzpatrick recovered from two early bogeys in a 69, a score matched by Spaniard Garcia, while Kitayama was bogey free as he went one better.
Spaniard Rafa Cabrera Bello and Belgium's Thomas Detry were at ten under, a shot clear of English pair Ross Fisher and Jack Senior, South African duo Zander Lombard and Louis Oosthuizen, and German Sebastian Heisele - who carded the lowest round of the day with a 64.