Erlandsson, 33, was seven under par on the last seven holes to card a nine-under 63 that gave him a two-stroke lead over compatriot Jarmo Sandelin and South African Richard Sterne.
It matched the score of Eamonn Darcy back in 1983, but the Brabazon course has been lengthened since then, so Erlandsson’s effort will stand as a new course record on its own in the eyes of the European Tour.
He has never won a European Tour event in 10 years as a professional and his previous best finish was second at the 2005 Wales Open.
But Erlandsson, who was only two under after 11 holes, eagled the long third, birdied the 442-yard next and then in the fading light closed with four more birdies thanks to putts of 14, 25, 10 and 10 feet.
He was delighted to come through a daunting run of holes in such impressive fashion.
“That’s definitely the toughest stretch, so I’m really pleased,” he said.
“It has got to be the best round of my career. I don’t think I missed a single shot. I was really spot-on with my swing.
“My card is secure for this year, so it’s a very different game. I’m more relaxed and can enjoy playing. It’s a good feeling.”