STOCKHOLM, June 7, 2012 (AFP) - Westwood followed up his first round 68 by hitting eight birdies to move to 12 under par ahead of a chasing trio of Scotland's Lloyd Saltman, Spaniard Carlos Del Moral and Swede Peter Hanson.
The Nordea Masters provided Westwood with his first European Tour victory in 1996 and he also won the event in 2000.
"I've always enjoyed coming to Sweden, obviously winning here for the first time in 1996 gave me an affinity," the world number three told Europeantour.com.
"And then I won again in 2000 when I won the money list so I've had a lot of success in Sweden and it's somewhere I enjoy coming to.
"I played nicely yesterday but today I played a little bit better.
"I'm getting to know the course a little bit better every day and it was there for the taking this morning. There was not a lot of wind and the greens were pretty pure.
"I'm putting the ball well and rolling it nicely on the greens which gives you confidence. I hit it pretty close so I gave myself a lot of chances."
Saltman, ranked 512th in the world, also carded a 64, including an albatross on the par five 12th.
Hanson, the 2008 winner, had a double bogey at the 11th but recovered with three birdies in his next four holes.
Spaniard Sergio Garcia threatened briefly, but he found water at the par five 13th and made 69 to finish the day six under in total.
Collated second round scores in the European Tour Nordea Masters at Bro Hoff Slott GC here on Thursday (Par 72):
132 - Lee Westwood (ENG) 68-64
135 - Carlos Del Moral (ESP) 68-67, Peter Hanson (SWE) 67-68, Lloyd Saltman (SCO) 71-64
136 - Emiliano Grillo (ARG) 68-68, Michael Jonzon (SWE) 68-68, Ignacio Garrido (ESP) 67-69, Maarten Lafeber (NED) 71-65, Richard Sterne (RSA) 69-67
137 - Richard Bland (ENG) 67-70, Chris Wood (ENG) 71-66, Magnus A Carlsson (SWE) 65-72
138 - Daniel Denison (ENG) 68-70, Roope Kakko (FIN) 70-68, Ross Fisher (ENG) 70-68, Sergio Garcia (ESP) 69-69, Estanislao Goya (ARG) 70-68, Joakim Lagergren (SWE) 70-68, Pelle Edberg (SWE) 69-69, Michael Hoey (NIR) 70-68
139 - Jeev Milkha Singh (IND) 73-66, Mikko Ilonen (FIN) 70-69, Kristoffer Broberg (SWE) 71-68, Felipe Aguilar (CHI) 69-70, Anthony Wall (ENG) 69-70, Andy Sullivan (ENG) 68-71, Thorbjorn Olesen (DEN) 71-68, Alejandro Canizares (ESP) 68-71, Gregory Havret (FRA) 70-69