Seeing the Majlis Course at Emirates Golf Club bring out the best in her for the third year in a row, MacDonald carded a second successive 68 for an eight under par total, two behind Anne Van Dam of the Netherlands.
Backing up MacDonald on the leaderboard are Michele Thomson, who sits joint sixth on six under, and Pamela Pretswell Asher, who is two shots further back in a tie for 14th in a strong field for the UAE event.
MacDonald, who started the day a shot off the lead, dropped a shot at the 11th – her second hole – before reeling off four birdies in a row from the 15th before recording another gain at the par-5 third.
Benefitting from having her good friend, Gullane PGA trainee Katy McNicoll on the bag, the former Scottish Women’s champion, holed from 10 feet to save par at her closing hole to sit handily placed heading with two rounds to go.
MacDonald finished 31st in this event in 2015 before claiming a share of 27th spot last year and has shaken off some poor results in the second half of the season to get herself into the mix again.
“I just lost confidence kind of during the year,” she said of having missed the cut in six of her last seven events on the circuit, a run that has left her languishing outside the top 90 on this season’s money list.
“But, having someone on the bag that’s reiterating, you know, my thoughts and going over the same things, is putting the confidence back into me.
“She’s a great friend, too, so that obviously helps.”
Thomson, who recorded her career-best performance when finishing runner-up in the Hero Women’s Indian Open last month, also signed for 68 in the second round. Her effort contained five birdies, including four in six holes from the 10th.
Needing a strong display this week to climb above Thomson and finish as the top Scot on the LET for the third season in a row, Prestwell Asher was bogey-free as she, too, posted four under par on day two.
A change of putter worked wonders for the big-hitting Van Dam, who covered the front nine in 30, five-under, to move to the top of the leaderboard on the back of a 65.
“I haven’t been putting great at all for the last half year, but I changed putters two days ago,” said the 22-year-old, from Arhem. “I went for something completely different. Normally I have face-balance and now I have toe-hang. It’s a blade, and normally I have a mallet.”
Also in contention is England’s Georgia Hall, who jumped from a share of 14th place overnight into joint third on seven-under after a 67. Alongside the Solheim Cup player are Australia’s Celina Yuan and Thailand’s Thidapa Suwannapura.
On a day when overnight leader Supamas Sangchan slipped to sixth after a 71, Gemma Dryburgh comfortably made the cut to four as she posted a 72 for a two-under total – a good effort given that she was a late arrival after gaining her LPGA Tour card in Florida on Sunday.
Two other Scots – Kylie Henry on level par and Vikki Laing, who made it with nothing to spare on one over – are through to the final 36 holes but Solheim Cup captain Catriona Matthew suffered a rare early exit on the circuit along with Carly Booth.
Among those to also miss the cut was Edinburgh-based American Beth Allen, who has a disappointing 12 months since she topped the LET money list.