The former world number one has not produced winning form so far this season but believes his game is running into good shape as he prepares for the year's second Major championship.
"I made a lot of birdies in the last two rounds, my game is coming around," the Englishman told Reuters after closing with a two-under-par 70 in the US PGA Tour event hosted by tournament founder Jack Nicklaus.
"Just a few too many mistakes so I've got to tidy up my control with the irons, keep hitting greens. I feel like I am putting better now."
Donald recorded six birdies in the third round and seven on Sunday on a challenging layout which had posed all sorts of problems for the players during the week, mainly because of lightning-fast greens.
In the final round, the gusting winds were not as severe and fickle as they had been on Friday and Saturday at Muirfield Village Golf Club, and he was delighted to take advantage.
"I am excited about where my game is heading," said Donald, who finished tied for 21st at one under.
"I certainly feel this year my play has been better than my scores and in previous years it has almost been the opposite. I have generally scored really well through a great short game.
"That's why I have never been too worried about some of my form this year because I feel as a player that I am hitting it pretty well. I'm just waiting for some things to happen, kind of fall into place."
Donald has recorded two top-10s in seven starts on the 2013 US Tour, his best finish a tie for third at the RBC Heritage in April.
On the European Tour, where he has won seven titles during his career, he missed the cut at the Malaysian Open in March and also at last month's flagship BMW PGA Championship.
Asked how much he could draw upon his week at Memorial going into the year's second Major, Donald replied: "There are some similarities with fast slopey greens where you can miss in the wrong places.
"Those are similar characteristics to a US Open so it's switching your brain in the right direction in terms of that and how to manage your way round the golf course.
"I made a few mental errors with some misses (at the Memorial) but I think all that is good. It engages your brain in the right way."
The US Open returns to the iconic Merion Golf Club in Ardmore, Pennsylvania for the first time since 1981, and Donald looks forward to the challenge of a layout measuring only 6,996 yards off the back tees.
"There's a mixture of some very long holes with some very short holes, so it has a good variety," the 35-year-old smiled. "Short game and wedges is going to be a priority. If I can do that well, then hopefully I will have a good week."
Perhaps surprisingly for many golf fans who regard Donald as a straight-shooter with a stellar short game, the Englishman does not have a particularly impressive US Open record.
He has three missed cuts and one withdrawal in nine starts, no top-10s and a best finish of joint 12th in the 2006 Open at Winged Foot.
"I always think there is a little bit of a misunderstanding of how people perceive me and how I perceive myself," said Donald, who has yet to win a Major title.
"I perceive myself as someone who is a really good short-game player, gets a lot out of my game but not necessarily someone who hits a lot of fairways and hits a lot of greens.
"Maybe in my early career I was a bit more like that but nowadays I am known more for my short game prowess. That would really explain my US Open record. At the US Open, you really have to have great ball control to be able to contend."
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