World No.2 Rory McIlroy and Thomas Bjorn shared the lead at the halfway stage of the Dubai Desert Classic on Friday.

At the $US2.5 million ($A2.33 million) European Tour event, the 2009 champion McIlroy posted an early bogey-free round of seven-under par 65 to set the pace, and his tally of 13-under par 131 was matched later in the day by the 2001 champion Bjorn (65).

Among those lurking behind the leading duo was German world number four Martin Kaymer (67) and English world NO.3 Lee Westwood (65).

Kaymer, who made the first hole-in-one of his life during the round, was tied for fourth place at 11-under par 133, while Westwood was another shot behind at 134.

Overnight leader Rafael Cabrera-Bello came in with a 69 to be at a 12-under par 132 to be one off the lead.

Tied alongside Kaymer were Frenchman Gregory Bourdy (67) and Scotland’s Scott Jamieson (68).

The day’s best round was by 2007 champion Henrik Stenson of Sweden.

An eight-under par 64 showed the Swede was reaping the reward for all the hard work put in after a knee surgery in December last year, and he surged to tied 11th place at 136.

Scoring continued to be easy in exceptional weather conditions and the cut was applied at one-under par 143 and 79 players, including American past champion Fred Couples and Mark O’Meara, made it to the weekend rounds.

McIlroy, who is now 14-under and bogey-free for his last 29 holes, hit 17 greens in regulation.

“I was never really under any pressure early in the round. I just got off to a much better start today and made a couple of birdies early on,” said the Northern Irishman.

Denmark’s Bjorn, who owns the tournament record of 22-under when he beat Tiger Woods in 2001, said his round was so solid, it was almost boring.

“I played well all day. I played the golf course in a way that I want to play the golf course. And you know, there was nothing that that stood out. I just played 18 solid holes of golf,” said Bjorn, who was also bogey-free in his round of 65.