WENTWORTH, May 24, 2014 (AFP) - The 43-year-old Dane fired a spectacular 67, including seven birdies in the final eight holes and coming home in an incredible 30, to show the rest of the field a clean pair of heels.
"I had a terrible start with some poor decisions but I settled myself down and knew I could play this back nine pretty well. I got the momentum and kept it going," he said.
"I'm in a strong position going into tomorrow but the job is not done yet. There is a lot of golf to play and I know there are top guys just behind me who can shoot very low as well. So I have to maintain my concentration and form to the end."
Bjorn, who produced a storming course record 62 on Thursday, suffered a double bogey at the first and then another dropped shot soon after.
But after falling back to seven under he turned in a stunning burst of birdies between 11 and 16 to set another record for consecutive birdies.
He had a shortish putt on 17 for another but it just grazed the outside of the hole to leave the Dane a little frustrated.
Yet he pulled himself together to finish in style with a seventh birdie on the back nine and complete another memorable day.
Now, not many would bet against Bjorn picking up his 16th European Tour title.
Ireland's Shane Lowry, who carded a disappointing 73, led at the start thanks to Bjorn's poor opening but he finished on eight under with England's Luke Donald, a two-time winner of this tournament, one stroke ahead of him.
Donald fired a fine 68 to be 10 under and the nearest challenger, and join Bjorn in the final group on Sunday. He birdied the final two holes while Northern Ireland's Rory McIlroy is a shot further back after a 69.
Donald said: "Thomas was on fire and it was hard staying close to him. I'm happy with a bogey free round but it will be very tough stopping him tomorrow if he continues in this vain. He's playing outstanding golf right now but it will be fun and exciting playing with him in the last pair."
McIlroy insisted: "I would have to shoot ridiculously low tomorrow to have any realistic chance but even then Thomas is so far ahead."
Heavy rain had delayed the start of the third round with the pairs becoming three-balls in order to get the round completed.
Italy's Franceso Molinari hit the lowest round of the day with a 65 but he's still nine shots adrift of the leader.
Scores from the third round of the European PGA Championship at Wentworth on Saturday (GBR/IRL unless stated; par 72):
201 - Thomas Bjorn (DEN) 62-72-67
206 - Luke Donald 71-67-68
207 - Shane Lowry 64-70-73
208 - Joost Luiten (NED) 70-71-67, Rory McIlroy 68-71-69
209 - Pablo Larrazabal (ESP) 69-71-69
210 - Francesco Molinari (ITA) 71-74-65, Anthony Wall 67-76-67, Jamie Donaldson 73-69-68, Eddie Pepperell 69-73-68, Chris Doak 69-72-69, Andy Sullivan 70-71-69, Thomas Aiken (RSA) 68-72-70, Henrik Stenson (SWE) 68-71-71
211 - Gary Stal (FRA) 66-76-69, Jonas Blixt 68-71-72, Rafa Cabrera-Bello (ESP) 65-73-73
212 - Simon Dyson 69-74-69, Martin Kaymer (GER) 68-75-69, Justin Rose 70-73-69, Marcel Siem (GER) 69-71-72, Fabrizio Zanotti (PAR) 67-72-73
213 - Stephen Gallacher 70-75-68, Richard Green (AUS) 70-73-70, Mark Foster 72-71-70, Mark Hooper 71-71-71, Marc Warren 73-69-71, Seve Benson 71-69-73
214 - Chris Wood 73-72-69, Alexander Levy (FRA) 71-73-70, Thorbjorn Olesen (DEN) 71-73-70, David Horsey 68-76-70, Richard Finch 71-72-71, Anders Hansen (DEN) 71-69-74
215 - Gregory Havret (FRA) 69-76-70, Tyrrell Hatton 75-70-70, Raphael Jacquelin (FRA) 70-75-70, George Coetzee (RS) 75-70-70, Alvaro Quiros (ESP) 73-72-70, Simon Thornton (IRL) 74-68-73, Bernd Wiesberger (AUT) 70-71-74
Selected
216 - Tom Lewis 73-72-71, Miguel Angel Jimenez (ESP) 72-72-72
219 - Thongchai Jaidee (THA) 72-73-74, Padraig Harrington (IRL) 69-76-74, Mikko Ilonen (FIN) 71-71-77