"It was the perfect start for me," McIlroy said.
"To shoot a great score like that really sets me for the next three days.
"I made three very good birdies on the front nine, hit it still on the first, third and fifth, but also made a couple of very silly mistakes. But I just stayed patient and the back nine was pretty much flawless."
The world No.2's putter was on fire on the back nine, as he made birdie putts of 12 feet on the 10th, 25 feet on the 13th, a 40-footer on the 16th, an 18-feet effort on the 17th and a slippery 20-footer on the 18th.
"I didn't expect Luke to play the way he did. I thought I needed to make a four-five under on the back nine," McIlroy said.
"But then every putt I looked at, it went in. It's not something that I experience often."
Donald's day was summed up when he took an unplayable on two consecutive holes on the back nine.
"It was a mixture of two halves really. I played solid the front nine and a couple of poor drives got me on the back," he said.
"But I am going to go to the driving range and sort out a few things for tomorrow. I will just try and get a little bit better from here on."
Hanson, who missed the course record when a birdie putt on the 18th from eight feet just slid past, was delighted with his bogey-free start.
"Of course, you cannot win a golf tournament after the first round, but you can always lose it," he said.
"I think it's the best golf I've played. It's quite a demanding course and the wind picked up a little bit over the back nine."