Karlsson’s 18-under-par, 54-hole total of 189 established a new European Tour record, eclipsing the 192 (18 under par) set by Tiger Woods at the NEC Invitational in 2000.

Paul Broadhurst is Karlsson’s nearest challenger on 12-under, but admitted his playing partner was making the Roman Road course look like “a pitch-and-putt”.

“Six shots is massive the way he is playing,” said Broadhurst, who carded a 67 containing six birdies and four bogeys. “He is playing amazingly so it’s going to be tough to catch him.

“I got within three shots after six but then caught a bad lie in the rough on seven and shanked a sand iron. If you hit a shot like that it’s going to unsettle you and it was tough to put it out of my mind.

“I’m going to have to try to put him under some sort of pressure tomorrow but he’s hitting it so far it’s like a pitch-and-putt course to him. I’m hitting it as far as I can and he’s still 30 or 40 yards past me.”

Karlsson held a four-shot lead overnight and a flawless front nine of 32 and a birdie on the 10th extended that advantage to seven.

A double bogey on the 14th where he found water with his approach from heavy rough – “It was a bad decision to go for the green” he admitted – briefly gave the chasing pack hope.

But a stunning drive and eight iron from 190 yards set up an eagle on the 16th to restore his cushion.

“There’s another 18 holes to go and if someone throws in a 61 behind me I will still have to play well to win,” insisted Karlsson, whose last tour victory was at the European Masters in Switzerland in 2002.

“If you start thinking that it’s yours to win then you are in big trouble. I’m trying to stay away from those sorts of thoughts all the time. I have to keep focused and I was happy with the way I did that today.

“The first time I looked at the leaderboard was on the 17th and I was surprised to see there weren’t more low scores.”

Victory on Sunday and the first prize would take Karlsson into the automatic qualifying places for the Ryder Cup, a contest he came agonisingly close to making in 1999.

“You can never make up for what happened but it would be a fantastic bonus,” added Karlsson, who finished 11th in the standings in 1999 and ninth in the final counting event, but was overlooked for a wild card by captain Mark James in favour of Andrew Coltart.

“But even if I win I would need almost as much again to make it and there are a lot of big tournaments left.”

Scotland’s Gary Orr is in outright third place after a 65 but Colin Montgomerie’s challenge petered out with a 69 to leave him nine off the lead.

“I’ve hit some really good iron shots this week but it’s frustrating that I made a lot of chances and couldn’t quite take them today,” Orr said.

“I am making plenty of birdies this week and I’ve played the back nine in 28 and 30 in successive days. I don’t suppose that constitutes a 58 though! I hope I can keep making birdies and cut out the silly mistakes.

“My game is getting close to what it was in 2000 when I had a couple of victories but I haven’t got the consistency I had then. Now I need more of the same tomorrow although it seems that somebody is going to need a really low score to catch Robert.

“He’s a proven front runner and this course suits him.”

Ireland's Graeme McDowell showed signs of a return to form with a five under par round of 64 to bring him to eight under for the tournament. Meanwhile, Michael Hoey is just one shot further back.

Peter Lawrie is on three under par while David Higgins is one shot back on two under.