The 35 year old had led by one overnight on 13 under par, but as he returned to the scene of his brilliant second round 61, he was no longer alone at the top of the leaderboard.
Korean pair Choi Ho-sung and Han Chang-won, Dutchman Joost Luiten, Northern Ireland's Gareth Maybin and India's Jeev Milkha Singh all joined Donaldson courtesy of good starts.
Choi's move was the most significant, seven adrift at the start of the day he birdied the first then fired an amazing sequence of six consecutive gains from the third to be seven under after 13 holes, although a run of five consecutive pars looked to have dampened his hopes of a first ever 59 on The European Tour.
His compatriot Han led after the first day when he fired a 64, but a two under 70 on day two had not been enough to sustain his position.
But three birdies in four holes put the 19 year old right back in the hunt for a first professional title.
Luiten, Singh and Maybin were all one under for the day over the opening holes, while an incredible 35 players were separated by just three shots at the head of affairs.
|T2||MARTIN BENAVIDES, Pablo||ESP||18||-20|