After making the cut on the mark at two under, the Dane - who has had encouragement from legendary former Manchester Untied goalkeeper Peter Schmeichel and tennis ace Caroline Wozniacki, both compatriots - carded six unanswered birdies in wet and windy conditions at Royal Portrush.That took the 22 year old to eight under par and a share of 11th as leader Grégory Bourdy of France was just starting his round.
The early clubhouse lead at eight under of Olesen, Scot Craig Lee (67) and Paraguay’s Fabrizio Zanotti (68) was looking increasingly competitive as Bourdy bogeyed the third to drop to 11 under.
Bourdy then three-putted the fourth for another bogey, missing from barely three feet.
That allowed Donaldson to take over at the top as conditions improved. He saved par with a 20 footer on the fourth and holed from ten feet for a birdie at the next to go 11 under.
Harrington bogeyed the fourth like Bourdy and slipped into a tie for sixth two behind.