World No.1 Rory McIlroy showed no signs of rust as he came out of a six-week break and raced straight to the top of the leaderboard on the opening day of the $US8 million ($A8.6 million) DP World Tour Championship.

McIlroy shot a bogey-free round of six-under par 66 to join his good friend Shane Lowry at the top.

Scotland’s Richie Ramsay and Denmark’s Thorbjorn Olesen were tied third one shot further behind at five-under par 67.

Defending champion and world No.4 Henrik Stenson opened with a four-under par 68 and was tied fifth along with Argentine Emiliano Grillo.

McIlroy, who has already secured the European Tour’s Race to Dubai crown, was playing his first competitive event since the first week of October.

The 25-year-old, who won both the tournament and the Race to Dubai in 2012 and is aiming for a repeat, started hot with four birdies in his first five holes, before adding two more on the 15th and 16th holes.

“Probably should have been five (birdies) in the first five, to be honest. It was a great way to start,” he said.

“You never expect to start like that, but I’ve been hitting the ball well for the last couple of weeks that I’ve been practicing and it was just a matter of trying to take that good range play on to the course, and I was able to do that today.”

Stenson, who won both the DP World Tour Championship and the Race to Dubai last year, was two-under par after six holes before making back-to-back bogeys on the seventh and eighth to fall back to even par.

But he recovered well with a birdie on the ninth and was solid on the back nine.

Wade Ormsby, the only Australian competing in Dubai, sits at one-over par in a share of 40th place.