Defending champion Adam Scott got back into the tournament with a third-round 66 and is alone in fourth place at 3-under-par 213.
'Defending a title is important and you want to hang on to it for as long as possible,' said Scott. 'Yesterday was disappointing because the poor way I finished almost shot myself out of the tournament. But I am playing well enough to win and all I need is to get a couple of putts going my way.'
Kjeldsen, who opened the third round with a one-shot lead, flew out of the gate Saturday. He drained a three-foot birdie putt at the first, two-putted for birdie at two and sank a 15-footer for birdie at the third to get to 7-under par for the tournament.
The Dane cooled off with three pars in a row from the fourth but after that run, it was back to birdies for Kjeldsen. He holed a pair of 10-footers at seven and eight to go to minus-9and take a firm edge over the rest of the field.
'Birdieing the first three holes and going out in 31 was unbelievable,' said Kjeldsen. 'I felt really good on the range and I knew what I was doing. I felt good out there and started making a few putts.'
Kjeldsen kept it going on the back nine when he ran home a 20-foot birdie putt at No. 11. He ran into trouble at the next, the par-5 12th, when his second shot landed in the rough and he failed to reach the putting surface with his third. Kjeldsen missed a 20-footer to save par but none of his competitors were threatening his lead.
Kjeldsen got back on track with a five-foot birdie putt at the 13th but once again, trouble loomed for the 28-year-old. At the 15th, Kjeldsen dropped his approach in a greenside bunker and he blasted out 15 feet long and right of the hole. He missed the par save and also missed an 18-footer to save par at No. 17 after his 4-iron approach missed the green right.
At Gleneagles' par-5 closing hole, Kjeldsen laid up short of the green with a 4-wood, then knocked his third to 12 feet. He made the putt to regain a five-shot lead and put himself in good position for his first victory on the European Tour.
'When I started this tournament, I felt I was playing well and my main goal was to give myself a chance on Sunday,' said Kjeldsen. 'I was leading going into today and I felt really good with it. I don't know how I'll feel tomorrow morning.'
Broadhurst started slowly on Saturday with a poor drive at the first and a bad 7-iron at six. He bogeyed both holes but rebounded with a birdie at No. 9. He tapped in a three-footer for birdie at the 12th and closed his round with a 20-foot birdie putt at No. 18.
'I struggled off the tee today,' admitted Broadhurst. 'The confidence in that part of the game wasn't there and that was the difference. But I hung in well and when I was 2-over after six, who knows what might have happened, I could have been looking at a 78.'
Forsyth was 2-under as he made his way to the 13th tee. He holed a four-foot birdie putt at the hole and added a 12-footer at No. 16. Forsyth bogeyed the 17th to lose possession of second place but all in all, the Scotsman was happy with his round on Saturday.
'Overall I'm pretty pleased with the way things went today,' he said. 'I played well, and drove the ball well around here which is crucial to give yourself a chance, largely kept out of trouble and in play.'
Colin Montgomerie (69), Stephen Gallacher (67) and Miguel Angel Martin (70) share fifth place at 2-under-par 214. Paul Casey (68), Gary Orr (72) and Rolf Muntz (73) are tied for eighth at minus-1.