MacDonald posted a two-under-par 70 in the third round at the Emirates Club to jump 11 spots into a tie for 11th with a two-under aggregate of 214.
The 25-year-old from Nairn was lying 98th on the money-list heading into the season-ending event in the UAE and needs to climb into the top 80 to escape a return to the Qualifying School in Morocco.
MacDonald is around £4,650 behind the player currently in 80th place, Australian Bree Arthur, and a top-20 finish would probably be good enough to see the Scot hang on to her card.
It’s been a bit of a struggle for MacDonald in her second season on the circuit, illustrated by the fact her best finish was 27th in the Aberdeen Asset Management Ladies Scottish Open at Dundonald Links.
But she’s saved the best for last so far and bagged four birdies, two in the last four holes, in making her positive thrust in the penultimate round.
That was once again dominatred by Feng as the world No 6 stretched her lead from two shots overnight to five heading into the final circuit after a third straight five-under 67.
Feng racked up five birdies in machine-like fashion on the front nine before dropping a shot at the 12th – her first in 48 holes.
She made another bogey on the 15th, but rebounded with a birdie on the 17th, inexorably moving closer to winning a record third time in Dubai.
Feng actually led by 10 shots at one point, but Thailand’s Thidapa Suwannapura fired a sizzling 65 – the tournament’s best score thus far – to jump to second on 10-under par.
Laura Davies, Feng’s nearest challenger at the start, slipped to 10th after a third-round 77.
After a one-under 71, Carly Booth is sitting joint-19th on one-under while Pamela Pretswell leapt up to a share of 41st on three-over after matching that third-round effort.
Sally Watson, the other Scot to survive the halfway cut, is joint-50th on four-over following a 73.