The 34-year-old Swede vaulted up the world rankings last year with four European Tour victories from July to November at the Scottish Open, European Masters, British Masters and Nedbank Golf Challenge.
Earlier in the day Japan's Hideto Tanihara went out early and had completed his round shortly after the leaders exited the first green having carded a best-of-the-day 5-under-par 67 which was good enough for tied fifth alongside Ireland's Shane Lowry and reigning Open champion Henrik Stenson on 4-under for the week.
"This has the feel of a major", he said.
"He's worked a lot on his game, sometimes maybe too much. I know I can play well around here, so I just try and do my thing".
"I had not thought of trying to win this morning", said Noren, who will move into the world's top 10 this week.
"That got me in trouble a few times and from there I'm sort of playing defense", Donald told Reuters in an interview after closing with a 76 and a 12-over-par tally of 300. "He's making progress and he's had a very impressive year".
Rose was set to miss the halfway cut after shanking a fairway bunker shot out of bounds on the sixth hole of his second round to run up a quadruple-bogey, but produced a grandstand finish with an eagle from 10 feet on the par-five 18th. He picked up another stroke at the 16th and then delivered a majestic five-iron approach to four feet on the last before sparking huge roars from the crowd by sinking his putt for an eagle three.
"It was probably one of the best shots I've ever hit".
"It feels fantastic", said the Swede in a presentation on the 18th green. I did not even think about it.
"I was pretty angry after the third round and then took a long rest and tried to just have a good day".
"But it's a great feeling now and a bit unreal".
In the third round, he struggled on the front nine with a double bogey and four bogeys and just one birdie, but he fired three birdies against no bogeys on the back nine.
The defending champion Chris Wood had always said that this year's BMW PGA Championship would witness low scoring. "I didn't really believe that the score would stand when I came off the course, but I did feel that it would be tough for someone to get to 12-under".
Molinari had a putt for the outright lead on the 18th but his eagle effort just drifted wide and he had to settle for a 70, two-under par whilst Pieters played solid golf for his 69. "There's a lot of positives (although) it's hard to kind of see them now". Lee Westwood, who started the day just three off the lead, did likewise to finish in a tie for 14th.