Kaymer and Fraser set the pace
Justin Rose made his first halfway cut in five visits to Doha, but it was Martin Kaymer and Marcus Fraser who were setting the pace.
Ryder Cup hero Kaymer had matched Rose's opening 68 at the Commercial Bank Qatar Masters, but on their return it was the German who really sparkled.
The man who sank the trophy-winning putt in Chicago in September added a 67 - just like Fraser - to be on the nine-under-par mark of 135.
They were a stroke ahead of Chilean Felipe Aguilar and South African George Coetzee, while Rose - who incurred a one-stroke penalty on the opening day when his ball moved as he prepared to tap in - shot 71 to be four behind.
Fraser parred every hole on the back nine, but then roared home in 31 with birdies at the first, second, fourth, sixth and seventh.
"It's one of those courses where you just have to keep plodding along and take your chances when they come," said the 34-year-old, whose only bogey so far came when he three-putted the short 13th on day one.
Kaymer had birdie twos on his card at the 17th, fourth and eighth, where he holed from nearly 20 feet, and also picked up shots on the long 18th and 452-yard fifth.
Rose, runner-up to Jamie Donaldson in Abu Dhabi on Sunday, was happy enough to turn in 34, but a wild second to the 591-yard first came as a real shock to the system.
It finished in the desert scrub and from there he needed three more shots just to make the green.
At least he limited the damage to a bogey six with a five-foot putt, but another shot went after he drove into a bunker on the sixth and he was very grateful for a 15-foot birdie putt two holes later.
Overnight leader Ricardo Santos, who began with a superb 65, was among the later starters, as were Ernie Els and Paul Lawrie - at level par needing to improve just to survive the cut - and Sergio Garcia, who set off again three under.