- Rory McIlroy and Thomas Bjorn lead Dubai Desert Classic at halfway stage
- Leaders on 13-under-par 131 at Emirates Golf Club
- Overnight leader Rafael Cabrera-Bello of Spain one shot back
- Martin Kaymer on 11-under scores hole in one on the 186-yard seventh hole
World No.2 Rory McIlroy and Denmark's Thomas Bjorn shared the halfway lead at the Dubai Desert Classic after both shot second round 65s at the Emirates Golf Club Friday.
It left the former winners on 13-under-par 131, one clear of overnight leader Rafael Cabrera-Bello of Spain, who carded a 69.
World No.4 Martin Kaymer of Germany was in a three-strong group on 11-under, boosted by his first-ever hole in one.
His eight-iron tee shot to the 186-yard seventh found the cup on his way to a 67.
"Now I'm part of the hole in one family," he told the European Tour official website.
Scotland's Scott Jamieson and Frenchman Gregory Bourdy joined him on that mark, while World No.3 Lee Westwood moved up with a 65 for 10-under 134 to boost his challenge.
U.S. Open champion McIlroy, out early after his first round 66, was again in imperious form as he reached the turn in four-under 33, having started on the 10th.
Watched by his girlfriend Caroline Wozniacki, the Northern Ireland star also missed an eagle chance from under 10 feet at the 18th and a short birdie putt on the first.
But with seven birdies and no dropped shots he left himself well-placed to repeat his 2009 success in Dubai.
"I just kept picking up birdies along the way and it puts me in a great position," he said
"I feel a lot more confident than I did in Abu Dhabi. "
Bjorn, who held off Tiger Woods to win the Dubai title in 2001, also carded seven birdies and said he was not overawed by the presence of McIlroy, Westwood and Kaymer at the top of the leaderboard.
It's very easy to get impressed by the way they play the game, but you've got to go out and focus on your own game," he said.
Abu Dhabi winner Robert Rock followed his opening 73 with a five-under 67 to stand four-under with defending champion Alvaro Quiros, Colin Montgomerie and Tom Lewis.
Last weekend's Qatar Masters champion Paul Lawrie was a shot further back.
The cut fell at one-under with American John Daly surviving despite a quadruple bogey eight at the 12th on his way to a 72.
Four previous holders of the title -- Mark O'Meara, Fred Couples, David Howell and Miguel Angle Jimenez - also scrapped in for the weekend on that mark.