Garcia added another birdie on the 461 yard eighth and by turning in a superb 31 had climbed all the way to joint 11th.
Ian Poulter was going in the opposite direction, however. A double bogey at the eighth sent him tumbling to 52nd place on one over.
There seemed no stopping Garcia at this point. When he made threes on the 437 yard tenth and 401 yard 11th he was seven under for the day, six under for the tournament and alongside McIlroy, Warren and Fernandez-Castaño in second place.
Breaking the course record of 64 was looking a distinct possibility.
Garcia's record bid hit trouble when he three-putted the 12th and failed to get up and down from short of the green on the 204-yard 13th, but he hit back spectacularly.
A 30 foot eagle putt circled the hole before dropping at the next and he took advantage of the tee being moved forward on the 15th, driving the green and two-putting for birdie.
At seven under he was joint leader - and not only with Donald.
German Marcel Siem also eagled the 14th and with birdies either side he was eight under for the day as well and needed one more birdie to set a new mark for the Greg Norman-designed Earth Course.