JOHANNESBURG, 5 Dec 2014 (AFP) - The 36-year-old former world number one from England carded nine birdies and just missed out on setting a new course record at the Sun City venue when he failed to birdie the final hole.
Donald's only threat appeared to come from a baboon which charged across the 13th fairway.
"We were walking up 13, saw one hiding in the tree, and got to my ball and suddenly (playing partner) Shane (Lowry) said, 'Watch out!'
"And I turned around and the thing is galloping towards me. I jumped out of the way.
"My facial expression I'm sure was caught on camera and probably on the internet already by now. It gave me a little bit of a fright as he strolled right by me.”
Overnight leader Ross Fisher slipped off the pace with a second round 70 to follow his opening 66 and stands in second place, two shots off the lead.
France's Alexander Levy is two shots adrift of Fisher and four off the lead and heads into the weekend in third place.
A year to the day since Nelson Mandela passed away, a minute’s silence was observed at the Gary Player Country Club in Sun City in memory of the former South Africa president.
Second round scores in the Nedbank Golf Challenge at the Gary Player Country Club, Sun City, South Africa on Friday (GBR/IRL unless stated; par 72):
134 - Luke Donald 71 63
136 - Ross Fisher 66 70
138 - Alexander Levy (FRA) 68 70
139 - Danny Willett 71 68
140 - Marcel Siem (GER) 68 72
141 - Charl Schwartzel (RSA) 70 71, Brendon Todd (USA) 73 68, Tommy Fleetwood 74 67, Tim Clark (RSA) 70 71, Thongchai Jaidee (THA) 71 70
142 - George Coetzee (RSA) 68 74, Lee Westwood 72 70
143 - Stephen Gallacher 70 73, Louis Oosthuizen (RSA) 70 73
144 - Brooks Koepka (USA) 70 74, Miguel Angel Jimenez (ESP) 70 74, Shane Lowry 72 72, Jonas Blixt (SWE) 71 73, Pablo Larrazabal (ESP) 73 71
145 - Kiradech Aphibarnrat (THA) 72 73, Dawie Van Der Walt (RSA) 73 72
146 - Joost Luiten (NED) 72 74
148 - Marc Warren 75 73
149 - Jaco Ahlers (RSA) 74 75, Martin Kaymer (GER) 74 75
150 - Kevin Na (USA) 77 73
152 - Thomas Bjorn (DEN) 80 72
154 - Mikko Ilonen (FIN) 76 78
155 - Danie Van Tonder (RSA) 77 78