Colsaerts bogey came after he missed a three footer at the first, but Goosen was having no such trouble with the flat stick and 20 footers at the second and third took him into the outright lead on 11 under.
Olazábal bogeyed the fourth, missing from five feet to fall two behind Goosen, before the double US Open Champion bogeyed the fourth after a poor pitch.
He was back alongside Schwartzel, with Olazábal alone in third after Grace double-bogeyed the third.
Olazábal was only one behind again after making a 12 footer on the short eighth and with Goosen mixing birdies with bogeys things could hardly be tighter.
He and Schwartzel were ten under, one ahead of three more Major Champions in Olazábal, Ernie Els and Louis Oosthuizen, as well as Colsaerts.
Harrington, though, fell six back with further bogeys on the seventh and eighth, but did at least birdie the long ninth to retain a slim chance.
The five par fives were always likely to play a big part and while Goosen ran up a seven on the ninth Els sank an 18 foot eagle putt at the 13th and jumped into a one shot lead.
He was five under for the day and 11 under for the tournament, one in front of Colsaerts and two ahead of Schwartzel and Grace, while Olazábal's bogey at the tenth left him three back.
Els followed his eagle with four pars in a row and was caught first by Colsaerts, then Grace, and then by Schwartzel as well after he came back from a double bogey at the 12th with an eagle and two birdies in the next three.
Goosen was one behind and Olazábal, two behind, was still not out of it with three to play.