The Swede leads Jarmo Sandelin and Richard Sterne by two strokes.
'I don't think I missed a single shot today,' said Erlandsson, who was 7 under on his final nine holes. 'I was spot-on with my swing,'
Soren Kjeldsen (66) three-putted his final hole and was tied fourth with Raphael Jacquelin. Rory McIlroy of Northern Ireland, playing his first tournament as a professional, shot a bogey-free 69, including chip-ins at the 11th and 12th holes.
Other notable players in the field include Lee Westwood (68), Colin Montgomerie (70), Paul McGinley (70), Robert Karlsson (71), David Howell (72) and Darren Clarke (74).
Erlandsson excelled on his second nine, starting with an eagle at the long third hole where he chipped in from 20 feet. He birdied the fourth and the last four holes.