Hanson, who has won only once in 174 European Tour starts, bogeyed the third hole but posted birdies on Nos. 5, 7 and 16.
I played well on the first nine holes, but I missed a few fairways on the last nine, said Hanson, whose only win was the 2005 Spanish Open. I must drive the ball better (Sunday).
Hanson, trying to become the first Swede to win this event since Jesper Parnevik 10 years ago, has a 54-hole total of 10-under 200 on the Arlandastad course north of Stockholm.
Hanson is 23rd in the European Ryder Cup standings but could still qualify for the team that will defend the trophy next month against the United States at Valhalla in Louisville, Ky.
I think Ive put myself a little bit too far back, but if I win tomorrow Ill change my mind about taking next week off, he said. I want to give myself every chance. Of course you can feel pressure playing at home, but I think its more inspirational.
Nick Dougherty of England (70), Swedes Daniel Chopra (67) and Pelle Edberg (66), Soren Kjeldsen of Denmark (68) and Gary Orr of Scotland (67) were tied for second.
Dougherty, last years runner-up, had two birdies and two bogeys on his card.
Im still in pretty good shape for tomorrow, he said. Six guys could win it. Its just lovely to be in contention going into the final round.
Dougherty shared the overnight lead with Hanson and they were atop the leaderboard heading to the 16th hole. Dougherty missed his short par putt, and Hanson birdied the hole to take control.
Dougherty is a two-time winner on the European tour. His last win came in the Dunhill Links Championship in Scotland last year, but he has not had a top-50 finish in seven starts following the death of his mother in April.
Patrik Sjoland (70) of Sweden and Sam Walker of England (64) were tied for seventh at 204.
Parnevik, the tournaments player-manager, shared 26th place at 208. Defending champion Mikko Ilonen of Finland was another shot back and in a tie for 40th.