The Swede had begun the day one stroke behind overnight leader Richard Bland but an unblemished round, that included six birdies, moved him on to 16-under par for the tournament.
The world number 26, who is chasing a third victory on the European Tour this year following his successes at the Scottish Open and the Omega European Masters, produced a particularly strong finish at The Grove, following up a birdie at the 17th with a successful 45-foot putt at the last.
The 34-year-old admitted after his round that it is always nice to end a day on a positive note.
He said: "Obviously on 18, it was an amazing feeling because I thought it was a tough putt, and you can easily three-putt that and come off with a sour taste in your mouth. Now it feels great. I've three-putted those a lot of times, so sometimes you've got to get lucky.
"I know from experience that it's not that easy to hold leads. Anybody can come from behind and shoot eight-under. You never know."
Englishman Bland holds second position on his own on 13-under, while Peter Hanson, Bernd Wiesberger, Richard Sterne and Tommy Fleetwood are all a further shot off the pace.