Defending champion Rory McIlroy was forced to settle for a share of fifth place on day two of the Dubai Desert Classic.
Asian number one Thongchai Jaidee carded a bogey-free second round of 66 to claim a one-shot halfway lead.
World number four Lee Westwood fired a flawless 65 in his best ever showing in 50 rounds at Emirates Golf Club to head the chasing pack at seven under alongside early pacesetters Stephen Dodd and Miguel Angel Jimenez.
McIlroy (70), Edoardo Molinari (70), Alvaro Quiros (69), Australia's Marcus Fraser (68) and Charl Schwartzel (70) are all well placed at six under, with a two-shot gap to Paul Casey (71), Graeme McDowell (68) and Jeev Milkha Singh (72).
McIlroy had earlier looked in ominous form, the world number nine briefly establishing a three-shot lead following a run of four consecutive birdies around the turn.
But the 20-year-old, who claimed his first and only career title to date with a wire-to-wire victory 12 months ago, found water at the last to card a double-bogey and round of 70.
"I am still happy where I am heading into the weekend. Apart from the mistake at the last it was another really good day's work. I putted really solidly, made a few birdies around the turn and also could have made a few more," said McIlroy.
"There is a little bit of a sour taste in the mouth after the last hole. I had not made a mistake all day and to do it at the last was disappointing, but if I make two birdies in the first two holes tomorrow all is forgotten."
© Press Association