DUBAI — Rory McIlroy endured a frustrating day on the greens at the Dubai Desert Classic Friday, but he still reached the tournament's halfway stage with a one stroke lead. The Ulsterman struggled off the tees early on in his second round, but by the turn he had briefly eased three strokes clear of the field, only for his putting woes and a charge by rising US star Brooks Koepka to keep him in check. McIlroy had a 70 to stand at 11-under 133, with Koepka, a year younger than McIlroy at 23, equaling the day's best round of 65 to get to 10-under. Two strokes further back on eight under came Damien McGrane (70) of Ireland, Englishman Danny Willett (65) and Julien Quesne of France (70). Defending champion Stephen Gallacher of Scotland (71) and European number one Henrik Stenson of Sweden (67) were among those on seven under. It was another disappointing day for Tiger Woods, who struggled with the putter all the way en route to a 73, which left him eight shots adrift of playing partner McIlroy and well down the field. Looking to make it two wins and a second place in his last three tournaments, McIlroy had the luxury of taking the morning off watching to see whether anyone could overhaul him after his stunning nine-under 63 on Thursday. Several challengers came and went, especially McGrane, Willett and Italian Ryder Cup star Edoardo Molinari. But no-one was able to dislodge McIlroy from the lead. Koepka, who opted to play on the European Tour Challenger circuit after graduating from his US college in May, 2012, was flawless with seven bogeys in his 65. Woods, playing in his second tournament of the year after missing the final cut at Torrey Pines last week, never looked like getting fully into his stride, despite an encouraging birdie at the third. World No. 3 Stenson moved ominously up the leaderboard as he recovered from a horror start to Thursday's opening round when he was three over after just five holes. The big Swede had five birdies in his 67 that hoisted him up the leaderboard at seven-under. Three-time former winner Ernie Els was also in better nick with a 70, but at level par for the tournament, the South African was just outside the projected cut mark. Yang and Watson set pace South Korean Yang Yong-eun birdied six of his last nine holes to surge into a share of the lead in the Phoenix Open first round while Phil Mickelson launched his title defense with a level-par 71 in Scottsdale, Arizona Thursday. Yang mixed eight birdies with a lone bogey to fire a seven-under-par 64 in dazzling desert sunshine. Yang's lead held up for most of the day until he was joined at the top by 2012 Masters champion Bubba Watson, who birdied four of his last six holes for a matching 64. Americans Pat Perez, Kevin Stadler, William McGirt, Harris English and Chris Kirk, along with Australians Greg Chalmers and Matt Jones, were a further stroke back after opening 65s. American Hunter Mahan, the 2010 champion, opened with a five-birdie 66 while England's former world No. 1 Lee Westwood carded a 67. — Agencies