The Northern Irishman had ended a disappointing first round with back-to-back birdies and he carried on where he left off with three birdies on the front nine - at the third, fourth and seventh.

The 10th, where he had all his problems in the final round last year, brought a three-putt bogey but he recovered with further birdies at the two par fives, 13 and 15.

A bogey at the 17th, after he drove into the trees, cost McIlroy a share of the lead but he avoided any additional damage with a fine up and down for par at the final hole.

"I drove the ball a lot better which I thought was the key for me today," he said.

"I was able to hit my ball from the fairway and attack the pins a bit more. I just felt a lot more comfortable out there today than I did yesterday and it added up to a better number.

Comfortable

"In the majors and at this course you just have to play your way into it and I felt I did that last night and went out there this morning and felt a bit more comfortable and was able to be aggressive.

"I am right where I want to be only off the lead going into the weekend. I have a chance to put myself in a position to win this tournament and I couldn't be more excited. I am just looking forward to tomorrow."

"I just wanted to come and play and put myself in position to win another tournament, another major."

Fred Couples, captain of the American Presidents Cup team last November, described it as "a little bizarre" to find himself out in front after a "magical" 67.

But it was not totally surprising. He has finished sixth and 15th over the last two years and said: "It's my favourite place in the world to play.

"On the range I felt my body tightening up a bit and I just wanted to play solid."