Gee had seven birdies, including at Nos. 17 and 18, against three bogeys for a 4-under-par 67. Sihwan Kim and Simon Wakefield, who each countered two bogeys with six birdies, are also 4-under.
Darren Fichardt, Raul Quiros and Raymond Russell are tied for fourth at 3-under and seven other players are knotted at 2-under 69.
Gee, who missed much of last season because of a hip injury, was among the early players and, after a bogey at No. 3 and birdies at 4 and 8, made the turn at 1-under. He had another birdie at the 10th hole.
Gee answered a bogey at 12 with back-to-back birdies at 13 and 14. After another bogey at 15 he had the closing birdies for the early clubhouse lead.
Kim was 3-under after 10 holes but had his first bogey at 11. He came back with birdies at Nos. 12 and 14 to get to 4-under for the first time. Kim dropped back with a bogey at the 15th hole but made 2 at the par-3 17th.
Simon, playing the second nine first, started with three birdies over his first five holes but also had back-to-back bogeys at 15 and 16. He played the front side in 3-under in getting his share of the lead.