US Open champion Rory McIlroy and Danish veteran Thomas Bjorn sunk late birdies to set the pace at the Dubai Desert Classic, with the pair 13-under after the second round.Behind them lurked Martin Kaymer - who claimed his first ever hole in one - and a resurgent Lee Westwood as golf’s top guns excelled on another windless day on Dubai’s Majlis course.McIlroy, Westwood and Kaymer are ranked two, three and four in the world, with only number one Luke Donald absent from the Dubai leaderboard. “This was very stress-free golf - fairways most of the time, a lot of greens and giving myself a lot of looks, so I’m really pleased with how I played today,” McIlroy, 22, told reporters.Yet the Northern Irishman may rue several missed long birdie chances as his putting often failed to match his stellar approach play.“It could have been better, I missed a putt on the 18th for an eagle, I missed a putt on the first for a birdie that was pretty short,” said McIlroy. “I hit a couple of really good putts on the back nine which could have dropped.”Germany’s Kaymer, on 11-under, said he would not be satisfied with a leaderboard finish. “The only thing that matters is the trophy - to leave the golf course on Sunday afternoon knowing that you have beaten everyone,” the 2010 U.S. PGA champion told reporters.“That’s the pure satisfaction. A few players say they want to win, but they don’t want it as much as others. Rory... he really wants to win and I’m not coming here to just play four rounds of golf in the sunshine.”McIlroy started the day on six-under, this time playing the back nine first. He teed off from the 10th hole early, a wisp of cloud shrouding the desert sun as Dubai slept on Friday, the Muslim holy day.The back nine in Dubai is kinder than the front nine, with three par-fives and a couple of short par-fours, so he was under pressure to score low early.CHIP SHOT.McIlroy sank a birdie on the opening hole, playing a chip shot from the rough to be within a few feet of the pin, but at the 11th he came up short with an 18-foot putt that would have earned a second successive birdie.McIlroy then missed a 25-foot eagle chance, but rolled in his next shot to move on to eight-under for the tournament.At two-under from seven second-round holes, McIlroy seemed frustrated, but on the 17th green he sank a fairway chip to gain a shot and this seemed to lift him as he holed a birdie on the 18th to be 10-under at the turn.On the front nine, and now cheered on by girlfriend and tennis player Caroline Wozniacki, he bagged three more birdies to score 65 for the round.Kaymer reached nine-under with three holes to play before sinking his debut hole-in-one.“I talked about it (a hole in one) a lot of times in the past few weeks, because I played with Sergio (Garcia) in Abu Dhabi,” added Kaymer.“I asked him how many do you have and he said ‘eight or nine’. Then Miguel (Jimenez) said he had stopped counting, so I thought at some stage it had to happen.”Westwood looked off the pace on Thursday and when reaching seven-under after 15 holes of the second round.Then he played a nine-iron chipshot on the 16th that rolled back to within a few inches of the pin for a birdie and went on to also pick up shots on the final two holes to end on 10-under.“I’d like for there to be a bit of breeze to keep it interesting and make a par and a bogey worth something because at the moment it’s a bit of a race-and-chase out there - sometimes if you don’t make a birdie every three holes you feel like you’re losing ground on the field,” the Englishman said.Overnight leader Rafael Cabrera-Bello, who shot 63 in the first round, ended Friday at 12-under as the Spaniard belied his lowly world ranking of 119.