Garcia fired a 64 to go a dizzying 19-under 194 for the tournament, eight shots ahead of Thailand's Thongchai Jaidee, who was an impressive 11-under for the tournament.
Garcia, who shot 63 on Friday, notched five birdies on the back nine after eagling the par-5 eighth hole for the second consecutive day. The former No. 2 in the world rankings bogeyed the third hole, his second of the tournament.
Ross McGowan ended the day in third place, one shot behind Jaidee at 10-under.