Two weeks ago at the Celtic Manor Resort Wales Open, Green opened with a 65 en route to an eventual share of ninth place. Just like his first round in Wales, Green's first 18 holes on Thursday were bogey-free.
'It was very much the same,' said Green. 'Here, like in Wales, I was very deliberate with all aspects of my game and I was in a great frame of mind so it was nice again to see that those things were working.'
Green played the back side first and picked up his first birdie of the day at the par-4 13th and added another at the par-3 17th to make the turn at minus-2.
The 1997 Dubai Desert Classic winner continued his steady play on the inward nine with a birdie at the second and reached 4-under with a birdie at the par-4 fifth.
Green saved his best for last, however, and turned it on with three birdies over his last three holes to finish at 7-under.
Andersson also reached 7-under late in his round but a bogey at his closing hole, the par-5 ninth, dropped him into second. Andersson, who also began on the 10th tee, torched the back half with six birdies to take the outright lead.
The 30-year-old reached 7-under with a 12-foot birdie at the fifth before falling one back of Green with his only bogey of the day at the ninth.
'Obviously it was a little disappointing to finish like that but overall I am very pleased with my performance,' said Andersson. 'I have been playing quite well over the past couple of months and I came into this week pretty confident.'
Andrew Oldcorn took the early lead with a birdie at the par-4 eighth, his 17th, to move to 6-under. However, the Scot found trouble at the very next hole to fall into a logjam at 5-under-par 67.
Oldcorn was joined by Ian Garbutt, Raymond Russell, Scott Gardiner, Jamie Spence, Adam Scott, Stephen Dodd, Raphael Jacquelin, Ignacio Garrido, Patrik Sjoland and Matthew Cort two shots off the lead.
Defending champion Paul Casey struggled at times but managed a round of even-par 72. Casey, who earned his first career win on the European Tour at this event last year, had six birdies on his round but faltered with four bogeys and a double bogey to finish seven shots back.
Warren Bennett, who won this event in a playoff over Rolf Muntz in 1999, also had a double bogey on his round. He added three birdies and two bogeys for a 1-over-par 73.
Full-field scores from Scottish PGA Championship