By Tony Jimenez

DUBAI (Reuters) - World number two Luke Donald made a flying start in his bid to record back-to-back victories by snatching the first-round lead at the DP World Tour Championship on Thursday.

Donald fired a seven-under 65 to move one stroke ahead of top-ranked Rory McIlroy, Briton Marc Warren and Gonzalo Fernandez-Castano of Spain at the European Tour's season-ending tournament.

Briton Donald, who won the Dunlop Phoenix title in Japan last week, struggled early and had to hole two medium-range putts to avoid dropping shots at two of the first four holes.

He then reeled off seven birdies in a scintillating 10-hole sweep from the fifth to overpower his rivals at a Greg Norman-designed Earth course softened by a monsoon-like downpour at the start of the day.

McIlroy, who has already clinched the money-list titles on both sides of the Atlantic, enjoyed his purple patch of form on the back nine as he squeezed five birdies into a seven-hole stretch from the 10th.

In joint fifth place on 67 were Ireland's Padraig Harrington, Swede Fredrik Andersson Hed, Martin Kaymer of Germany, British pair Lee Westwood and Richie Ramsay and South Africa's Louis Oosthuizen.

(Editing by Tom Pilcher)