GOLF: Rory McIlroy puts himself back in contention at British Masters
The Northern Ireland man is part of a five-strong group on 10 under.
That includes Karlsson's fellow Swede David Lingmerth, who shot an eight-under-par 62 in Newcastle on Saturday.
Advertisement
Hide AdAdvertisement
Hide AdEngland's Ian Poulter, Graeme Storm and Tyrrell Hatton are one off the lead in a five-way tie with Scotland's Richie Ramsay and Ireland's Paul Dunne.
"You get yourself into contention and you start to think about things and it would be nice to get a win," said McIlroy.
The four-time major winner was a late entry at Close House after failing to qualify for the Tour Championship.
"The crowds have been fantastic," added the 28-year-old, who made six birdies without a blemish on his card in the third round.
Advertisement
Hide AdAdvertisement
Hide Ad"The last couple of tournaments I've been off pretty early on the weekends and had 50 people following me, where there's thousands out there so it's nice to get into that sort of environment again."
McIlroy is on course for only the second winless season of his career.
While McIlroy is happy with the crowds, Poulter was seething about being distracted by spectators taking pictures on their mobile phones.
"What are we doing?" he said. "We've allowed them all to take pictures and videos and tell them to put them on silent, and it doesn't work does it?"
Advertisement
Hide AdAdvertisement
Hide AdAsked if mobile phones should be banned, Poulter added: "No, I just think people need to educate themselves and understand it's an issue for us and them.
"They don't realise they distract us as much as they do - 99% of them are on silent and unfortunately there's a couple which are not.
"You're not expecting it because you think they've got it on silent. I'm angry and am going to continue to be angry until I wake up tomorrow morning.
"Throwing shots away for no reason is really annoying."