Rory McIlroy & Luke Donald level in Dubai

World number one Rory McIlroy carded a 67 to share a one-stroke halfway lead with Luke Donald and Marc Warren at the DP World Tour Championship in Dubai.

The 23-year-old birdied the first two holes and made a solitary bogey in reaching 11 under, while Warren also had five birdies and a bogey in a 67.

Donald birdied the last for a 68 and is yet to drop a shot in the tournament.

Sergio Garcia is four back after a remarkable 64 containing nine birdies, two eagles and a quadruple bogey.

McIlroy, whose only dropped shot came at the 245-yard par-three fourth, saw several opportunities slip by and admitted: "It could have been lower."

He revealed he had been affected by the heat in Dubai and said: "I got off the course yesterday and had a really sore head and a fever. I think it was a bit of sunstroke. I took a few things and felt better, but I'm not feeling great again. The sun's taking it out of me a bit."

Asked about his game he said: "I'm driving the ball really well and I feel there could be something in the low 60s for me - compared to previous years the course is probably a bit more receptive."

Donald was also unable to emulate his sublime putting touch from round one but finished in majestic fashion with a pitch to within two feet from 150 yards.

Should he complete the final two rounds without dropping a shot he would be the first man to do so on the European Tour since Jesper Parnevik in 1995.

Competing in his first event since having laser eye surgery after the Ryder Cup, Garcia opened with a modest 73 but birdied four of the first five holes on day two and had only four pars in his round, none of which came after the ninth.

His seven at the 16th came after an eight-iron found the water but he then picked up three shots in the final two holes, finishing with an eagle at the last after his drive bounced back into play off a rock in the stream down the left-side of the fairway.

From there the 32-year-old Spaniard sent a five wood to 20 feet and holed the putt to equal the lowest score at the Greg Norman-designed Earth Course.

"I wish I could explain that," said Garcia of his colourful round, the sixth 64 in the four-year history of the lay-out.

Meanwhile, former world number one Lee Westwood is a distant eight shots off the pace after seeing three shots slip away in his closing three holes en route to a 74.

There is no cut in the 56-man field for the final event of the European Tour season but 2010 US Open champion Graeme McDowell is 12 strokes adrift after dropping four shots in a round of 73.