He has won tournaments on both sides of the Atlantic Ocean this year, yet for all his success the Briton remains dogged by one glaring omission from his CV, a Major championship title.
In the lead-up to this week's US Open, Donald has almost gone unnoticed. When Tiger Woods and Rory McIlroy held their pre-tournament news conferences on Tuesday, it was standing room only in the interview room.
When Donald came in, only a dozen or so reporters were there to quiz him on his preparations.
"It doesn't really, whether I'm ranked number one or ranked number 10 or 20 or 100, it doesn't change the way I prepare or the way I practice," he said.
"The focus for me is to continually try and improve and get better in all facets of my game and that has no relevance to where my world ranking is.
"The only other slight distraction, which is less so for me because I kind of go under the radar, is as a number one ranked player is that there's more, a little bit more attention, a little bit more expectation."
Although he has not won a Major, Donald has come close a few times, finishing in the top five at the Masters, The Open and the US PGA Championship.
The only Major he has not finished in the Top 10, is the US Open, which is traditionally set up to be the hardest to play.
"US Opens are tough. It challenges every part of your game from the first tee shot to when you walk off 18," he said.
"I think out of all the Major championships, this is the toughest test in a way. Most of the time par is a good score and it's a grind out there."
Donald has not finished higher than 45th at the US Open since he tied for 12th in 2006, but despite his poor record, he is confident of a good showing this year at the Olympic Club, a tricky course which he thinks suits his game because of his preference for shaping the ball from left to right.
"I feel that most of the tee shots out there fit reasonably well with my eye. I feel more comfortable and more in control of the ball if I'm hitting a slight fade," he said.
"The draw, over the last past couple years has been a tougher shot for me to hit consistently and start on the right line.
"The fade is a little bit easier shot. I think that's probably the same for the majority of the players. So as this course demands a few more of those, I feel like it suits my eye reasonably well."