Donaldson completed a first round of 67 on Friday morning, play resuming at 7:30am after being abandoned for the day on Thursday afternoon after a second thunderstorm hit the course.
That left the 38-year-old one shot behind Spain's Sergio Garcia, but a second round of 66 containing seven birdies and just one bogey took Donaldson to the top of the leaderboard.
The solitary dropped shot came on the par-five 10th after a front nine of 31,Donaldson finding a fairway bunker off the tee and hitting the lip of the bunker with his second shot.
Unluckily, the ball bounced back and hit the shaft of Donaldson's club as he followed through, sending the ball back into the sand and resulting in a one-shot penalty.
However, after hitting his fourth shot down the fairway, Donaldson fired a superb approach from 150 yards to within a few feet of the pin to limit the damage, before picking up further shots on the 13th and 14th.
"These bizarre things happen and you just have to get on with it," said Donaldson, who won his second European Tour title in Abu Dhabi in January and finished fifth in the 2013 Race to Dubai. "In the end it was a good six!
"I've played very nicely for the first two rounds and hit a lot of good shots so I am happy with the way I am playing. We had to play six holes of the first round and then back out after a 45-minute break for the second, so it's been a long day."
European number one Henrik Stenson and American Ryan Moore share second place on eight under, Moore shooting the lowest round of the day with a 65 and Stenson returning a 67, with neither player dropping a shot.
Defending champion Martin Kaymer and Denmark's Thomas Bjorn are a shot further back, with Garcia dropping back to five under after struggling to a 73.