Oosthuizen three clear in Qatar Masters

(CNN) -- South African Louis Oosthuizen carded a flawless seven-under-par round of 65 to claim a three-stroke halfway lead at the Qatar Masters on Friday.

Oosthuizen, the runner-up in last week's Abu Dhabi tournament, battled early afternoon rain to reach the turn in three-under -- before taking advantage of calming conditions to move onto 12-under-par and establish a sizeable advantage over former champion Andrew Coltart.

Scot Coltart, who was victorious here 11 years ago, hit a three-under 69 to hold the clubhouse advantage before Oosthuizen's intervention.

Portugal Masters champion Alvaro Quiros of Spain leapt up the leaderboard and into third place with a five-under 67 which included a hat-trick of birdies to finish.

He is joined on eight-under by Australia's Brett Rumford who signed for a solid 69 which included just a solitary bogey.

Miguel Angel Jimenez, who held the overnight lead with Coltart and another former champion Henrik Stenson, sits five adrift in fourth place after a solid one-under 71.

After dropping just one bogey in his opening round 67 on Thursday, Oosthuizen, 26, picked up a first shot of the second round at the 452-yard par-four fifth before blazing around the turn with four birdies in five holes.

Back-to-back birdies from the 15th quickly followed to put the two-time South African PGA Champion well in the hunt for a maiden European Tour victory.

"I am playing well and I am very happy," Oosthuizen told the UK's Press Association. "It's always a nice confidence boost to play well the week before and that second spot was very close to a play-off. It was nice bringing that form to Qatar and I am very happy."

Stenson, the 2006 champion, could only manage a level-par 72 to remain at six-under alongside Ireland's Damien McGrane (69) and Paul Broadhurst (70), while Lee Westwood need three late birdies to salvage a 73 and dropped into a tie for 16th alongside world number two Sergio Garcia, who signed for a second consecutive 70, at four-under.

Defending champion Adam Scott, who has a 100 per cent record at Doha Golf Club after also winning in 2002, carded a second-round 70 to move to one-under-par.

At the other end of the leaderboard, American Ryder Cup star Boo Weekley (73), Abu Dhabi winner Paul Casey (69), Justin Rose (72) and Colin Montgomerie (75) all missed the cut.