Bjorn played just three holes of his third round which he is due to complete on Sunday after play was suspended due to darkness.
Having added a 67 to his first-round 66, Bjorn - one of a number of players who did not play at all on Friday due to thunderstorms - had parred the first three holes when a halt was called and is at nine under.
Bjorn told the European Tour website after completing his second round: "This course can very quickly bite you, especially if you don't drive the ball well. The numbers can run up on this golf course, so you've got to stay with what you're doing.
"I've enjoyed these two days, and it's nice to play some good stuff but there's still a long way to go in this golf tournament. I've got two good rounds in the bank but there's a way to go."
South Africa's George Coetzee and England's Chris Wood, both looking for a maiden victory on the European Tour, ended the second round level but the latter carded a birdie on the second hole of his third round to sit one stroke behind Bjorn.
That was one shot ahead of world number one Rory McIlory.