By Sportsmail Reporter
PUBLISHED: 14:44 EST, 26 May 2012 | UPDATED: 14:47 EST, 26 May 2012
Luke Donald is on course to retain his BMW PGA Championship title - and to return to world number one - after a nightmare day for overnight leader James Morrison in front of family and friends at Wentworth.
Four clear after a sparkling second round 64, the world number 236 crashed to an 81 and will go into the closing 18 holes an amazing eight strokes behind.
While local man Morrison had a quadruple bogey eight, a triple bogey eight and three bogeys on his card, Donald showed his class with a 69 - the joint best round of the day in the windy conditions.
Leading the way: Donald
Needing only a top eight finish to take the number one spot back off Rory McIlroy, who opened the door by missing a second successive cut, the 34-year-old is now 11 under par and two ahead of Justin Rose.
Donald is trying to follow Sir Nick Faldo and Colin Montgomerie as the only players to make a successful defence of the European Tour's flagship event.
Faldo did it in 1980 and 1981, while Montgomerie had three wins in a row from 1998 to 2000.
Former England Youth cricketer Morrison, whose only win on the circuit was in the relatively minor Madeira Islands Open in his rookie season two years ago, knew it was going to be a test for him.
'I desperately, desperately, desperately want to keep going forward,' he had said. 'I expect a lot, but if I shoot 80 or 65 I'll take what I can from it.'
He could never have expected things to unravel as they did, however.
Falling apart: Morrison had a terrible day
After a bogey on the first, where he bunkered his approach, he went out of bounds with his second on the long fourth and ran up his first eight.
That alone was enough to take him out of the lead, but the collapse continued.
He bogeyed the next and on the 391-yard eighth went from trees to water for a quadruple bogey that was matched by playing partner David Drysdale, himself twice in the lake.
The Scot had been joint leader at that point, but that was the start of a horrible slide for him too. He finished with a 78.
Donald plotted his way around like the expert he now is, gathering birdies at the first two par fives and then going two clear at the 13th.
Peter Lawrie was the man out in front with them by then, but as the Dubliner hit into the trees and bogeyed Donald fired in an iron to six feet and picked up another shot.
He did bogey the 15th after driving into a ditch, but salvaged a par on the long 17th after going in the trees and hitting an on-course television reporter with his next shot.
Losing his way: Lawrie
Then, to nobody's surprise, he laid up short of the water on the last, pitched to 18 feet and made it.
Rose, who played with Donald the first two days and admired his ability to bounce straight back from trouble, and Ian Poulter were the only others to break 70.
Lawrie is in third spot on seven under after a 72, while joint fourth are former Open champion Paul Lawrie and South African trio Branden Grace, Richard Sterne and Ernie Els - the latter livid with the lack of watering on the course he re-designed.
Donald said: 'The tougher the better. The good players that can be patient and deal with it are always going to rise to the top usually.'
The US Open is generally regarded as the hardest of all the majors and with it coming up in just over a fortnight Donald said this week was "good prep.
'That was by far my best round of the three. The swing was swirling and I hit a lot of solid shots.
'There were a couple of loose ones coming down the stretch, but I'm very pleased with that finish - it was hugely important for me.
'Physically and mentally it was tough and it's going to be a grind tomorrow.'
Rose, who could move to a career-high fifth in the world by winning, commented: 'I'm delighted. It was one of those where I realise how good a round it was until I saw that the course had taken its toll.
'There were some borderline holes, as there are at US Opens and on Sundays, but I sort of relished the challenge. It takes all your experience and patience and it certainly tested me.'