Luke Donald in charge after superb 64 at Wentworth

Luke Donald shot an opening seven-under 64 to throw down the gauntlet at the PGA Championship at Wentworth.

Britain's world number two equalled his best ever round on the European Tour on a blustery, damp morning in Surrey and held firm to end the day.

He leads by two shots from 18-year-old Italian Matteo Manassero and Sweden's Johan Edfors.

Another Swede, Oscar Floren, was four under after 14 holes when darkness fell to end his climb up the leaderboard.

A 36-minute delay for thunder and lightning during the afternoon left several players with unfinished rounds.

England's Ian Poulter and Ross McGowan, Welshman Bradley Dredge and Spaniard Jose Manuel Lara were three under.

Europe's 2010 Ryder Cup captain Colin Montgomerie also lit up the morning with some vintage golf to lead alongside Donald for a spell before slipping back to a two-under 69.

Northern Ireland's Darren Clarke, who won the Iberdrola Open in Mallorca two weeks ago, also ended two under alongside Alvaro Quiros, Thomas Levet, Kenneth Ferrie and two-time winner Anders Hansen.

Lee Westwood, who could lose his world number one ranking to Donald or Martin Kaymer this week, carded a one-over 72.

The four current major champions on show were unable to impress, though, as USPGA winner Kaymer carded 74, US Open holder Graeme McDowell shot 75, Open champion Louis Oosthuizen took 76 and Masters victor Charl Schwartzel amassed 79.

But England's Donald, 33, underlined his pedigree as the form player in world golf with his best score over the West Course.

The WGC Match Play champion, who finished second to Poulter in the World Match Play last week, picked up shots at the fourth, sixth, seventh and ninth and added further birdies at 10, 13 and 16 and 17. His only bogey came at the 480-yard par-four 12th.

"That's probably one of the best rounds I have ever played," said Donald, who led at halfway last year and ended up tied for second, one shot adrift of winner Simon Khan after double-bogeying the penultimate hole when in the lead.

"They were tough conditions out there, the wind was swirling and there were some rain showers.

"I felt totally in control and that doesn't happen very often in golf. I felt a little bit invincible."

Manassero, who received the European Tour Rookie of the Year award on Monday, said the West Course suits him "because you have to put the ball in play".

The two-time Tour winner, who has another year of studies left and will take exams after his first appearance at the US Open in June, said his confidence is improving all the time.

"Seeing yourself on the leaderboard gives you confidence," said the Italian, who only turned pro last year. "I'm changing the swing a little bit so I'm still not exactly where I want to be with it but I'm getting better all the time."

The 47-year-old Montgomerie, who won the PGA Championship three years in a row from 1998, was five under after eight holes and also made birdies at 11 and 13 but struggled to maintain his momentum over the back nine and dropped shots at the 10th, 12th, 15th,16th and 17th.

But despite the poor finish the eight-time European number one was able to remain upbeat. "I can see well beyond that, seven birdies is encouraging, no question," he said. "OK, five mistakes but you are going to make mistakes out there, it is extremely difficult."

Montgomerie, whose last victory came at the European Open in 2007, has struggled in recent years and has dropped to 462nd in the world.

"It's been a very poor last three years. It's been awful," he said. "But I've been working a little bit harder on my game. I would like to get back in the top 50.There must be something going on that's right, there's just too many wrongs."

Montgomerie also revealed his caddie left him at the weekend. "I usually did the sacking, now it's the other way around," he said. "He has gone with Francesco Molinari. I'm caddieless. I've borrowed Thomas Bjorn's caddie for this week."

Westwood admitted his putting had again cost him after trading three birdies with two bogeys, plus a double bogey at the sixth.

"When your longest putt is five feet you are going to struggle to shoot seven under," he said.

"I had only one bad swing - left into a bush on the sixth."

South Korea's 2009 USPGA champion YE Yang fired a level-par 71, England's Paul Casey took 72, his countryman Justin Rose signed for a 75 alongside Ernie Els, the man who oversaw the recent course changes, and Northern Ireland's Rory McIlroy shot 76.

Europe's Ryder Cup captain Jose Maria Olazabal retired with a back problem after seven holes. The 45-year-old, who has been plagued by rheumatism in recent years, was five over par.