Donaldson said later: "It was one of those rounds where you hit every shot where you want to and every putt where you want to.
"I played great from the word go, hit a lot of fairways and put myself in really strong positions and capitalised when I had putts. I didn't have many long putts, just played really well, and one of those days where everything went for me. It's been a really good day.
"The course suits me. The fairways are quite generous and if you miss the bunkers you can play aggressive golf.
"It's an awesome field, so I need to keep playing like that to stay ahead of them. The strength and depth across The European Tour nowadays seems to be very strong - it's just particularly strong this week."
Meanwhile, despite his impressive 67, McIlroy didn't feel he'd done anything special.
"It was okay," said the world number one. "I didn't feel I did anything spectacularly out there. I just played some solid golf.
"The targets on this golf course are big... big fairway, big greens so you're going to give yourself plenty of chances out there.
"It was a good, solid round of golf."
