The world number two, who triumphed here in 2009 for his first professional title, started at the tenth and made seven birdies to secure a blemish free round early in the day.

"I just kept picking up birdies along the way and it puts me in a great position," the 22 year-old said after his round.

"I feel a lot more confident than I did in Abu Dhabi."

It wasn't long however before Bjorn sunk enough birdies to catch up to the US Open champion, and joined him at the top of the leaderboard - one shot clear of overnight leader Rafael Cabrera-Bello.

"There's a tricky spell on this golf course, six through nine, and that can really come up and bite you," explained the 40 year-old Dane, who won this tournament in 2001.

"You've got to keep your patience because the back nine offers a lot of opportunities."

At eleven under is a group of three players including Germany's Martin Kaymer, who made shot of the day with an impressive hole-in-one at the 186 yard seventh - a first for the world number four.

Alongside Kaymer and McIlroy, Lee Westwood also poses a challenge to the early leader at ten under, but the threat of these three big names isn't enough to put Bjorn off his game.

"The good thing for me is I won in Switzerland (September's Omega European Masters) with those three on the leaderboard as well and that's not too long ago," he said confidently.