The 32-year-old Spaniard, who had seven weeks off after his treatment to correct astigmatism, birdied four of his first five holes to move to three under par at the European Tour's season-ending DP World Tour Championship.
He had resumed joint 49th out of only 56, but was up to 21st spot only four behind leader Luke Donald.
Last year's leading money-winner had opened with a bogey-free 65 for a one-stroke advantage over this season's leading money-winner Rory McIlroy, Scot Marc Warren and Garcia's compatriot Gonzalo Fernandez-Castano.
Austrian Bernd Wiesberger made a good start, birdies at the first and third lifting him to two under, but England's Richard Finch, at 228th in the world the lowest-ranked player taking part, was losing touch with the rest when bogeys at the seventh and eighth dropped him to six over.
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 10th and 401-yard 11th he was seven under for the day, six under for the tournament and alongside McIlroy, Warren and Fernandez-Castano 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.