Ted Oh is alone in fourth place at 7-under-par 64. Daniel Chopra, Simon Dyson, Alessandro Tadini and Wei-Tze Yeh are one shot further back at minus-6 65.
Andersson, who started on the back nine at The Mines Resort & Golf Club, opened with birdies on each of his first two holes. After a trio of pars, he caught fire towards the end of the nine. Andersson birdied the short par-4 15th, then closed the side with consecutive birdies starting at the 17th.
Around the turn, Andersson made it three straight birdies, and four in a five-hole stretch, with a birdie at the par-4 first. He converted back-to-back birdies again, this time starting at the third to move to minus-8. Andersson's final birdie of the round came at the sixth hole, where he chipped in from 35 yards out.
'I haven't played that well this year but the game has been feeling better,' said Andersson. 'Even though I haven't had the results I was hoping for, it was going to come and I had a lot of fun out there today.'
Atwal, who also began his round on the back nine, had a pair of impressive birdie runs during his round. The 2002 Caltex Singapore Masters champion got into red figures with birdie at the par-5 11th. After a pair of pars, Atwal had the first of two birdie outbursts. Beginning at the par-3 14th, he ran off four consecutive birdies to climb to 5-under for his first nine holes.
On the front side, Atwal's second nine, he again posted four consecutive birdies this time beginning at the par-5 third to climb into a share of the lead. He had a chance to claim first place by himself, but he parred his final four holes to remain tied atop the leaderboard.
'Everything went well,' said Atwal, who birdied all three par-5s. 'I drove the ball well, put myself on a lot of fairways and then putted really well which was the key. I killed the par-5s and it was a lot of fun.'
Srirot began his round with a birdie at the first. He later carded back-to-back birdies beginning at the fifth. He posted pars the last four holes of the front side to make the turn at 3-under-par.
On the back nine, Srirot notched consecutive birdies starting at the par-4 12th. He drained his final birdie of the round at the 15th. He vaulted into second place when he holed out for eagle at the par-5 17th.
Retief Goosen, Simon Yates, Periasamy Gunasagaran, Padraig Harrington, Harmeet Kahlon, Wook-Soon Kang, Dean Robertson, Gary Rusnak and Lee Westwood share ninth place at 5-under-par 66. Harrington was pleased with his performance coming off a nine-week layoff.
'Nine weeks off and to shoot 5-under is just great,' said Harrington. 'I am surprised. But I had done the work on my game and my mind was very active so it was getting better as the days went on and it was better today.'