"I've been marking my ball with a loonie all week", said McIlroy, in his post-win press conference.
On top of the US (2011) and British (2014) Opens, McIlroy has also won the Australian (2013) and Irish Opens (2016).
"If I didn't have a big tournament next week, I would be sticking around for that Game 5", said McIlroy, who is also friends with L.A. Lakers superstar LeBron James and been his guest at previous NBA Finals. "I played an RBC day on Tuesday over in Mississauga".
It seems like McIlroy can add some Raptors to his championship-worthy repertoire of birdies and eagles from Sunday. He made four consecutive birdies from Nos.
On the 18th, McIlroy found the greenside bunker but went for it with his third. He ended up tapping in for bogey to finish at a tournament-record 22-under 258.
McIlroy has shot 63 (in the 2010 Open Championship) and an -11 score of 61 (in 2015 at the Wells Fargo Championship) before but this was the lowest round of his pro career.
"You're sort of just hanging on, playing into the right spots, and I felt like this week I was free. I've really enjoyed my time here".
"I did that, and I think that's the reason that I played so well was the fact that I put myself in the fairway for the most part. I had to reassess my goals a little bit in the middle of that back nine".
He settled for his 16th PGA Tour victory and 25th win worldwide, and the fourth by at least seven shots.
Simpson (68) fell into a tie for second with Shane Lowry (67).
The Clara native's second place finish at the Canadian Open has seen him move up 10 places to 32nd in the rankings.
McIlroy began the day tied atop the leaderboard with Matt Kuchar and Webb Simpson, but the North Irishman was untouchable after four birdies on his first five holes. It had 12 feet of break on it. A clutch putt for par was needed on the 18th but, from a monster 35 feet out, McDowell held his nerve. "Just fancied it, I saw it, liked the way it looked, and when I saw it go in it was a huge relief".
"Obviously, the chase for the Open Championship at Portrush and getting my spot for that, it's really been a journey since Bay Hill this year, the first tournament that had some sports [available] for the Open Championship".
As welcome as the top-10 finish was for the 39-year-old, securing a spot in the final Major of the year in his home town of Portrush, with a couple of weeks to spare, meant a whole lot more. I'm excited. Got to make short putts, long putts at the U.S. Open to contend, and so I'm excited for next week. "I might go to Portrush and miss the cut and think, 'What was that all about?'"