Clark sunk five late birdies in the last eight holes to card five-under-par 65, having started the round with a bogey.
Overall, he finished on 17-under 263 to claim his second PGA Tour title since winning the 2010 Players Championship.
“It looked like Jim wasn’t going to make any mistakes,” Clark told Associated Press. “He was pretty solid, so I knew I had to make birdies. At that point, there was nothing to lose. Suddenly I got hot and I went with it.
“Once he missed his putt, I didn’t want to have to go into a playoff, knowing he can take it over the water (off the 18th tee) and I have to play over to the right. So, it was huge for me to get it finished right there. I got hot with the putter on the back nine. To stand over that putt and still feel confident was really nice.”
Clark, who is married to a Canadian wife, won his first professional title at the New Brunswick Open on the Canadian Tour in 1998.
“The irony of it is Canada could be the location of my first win and my last one,” Clark said. “To come back here, it’s full circle. That was 16 years ago when I was just cutting my teeth as a professional golfer and I was fortunate enough to be given some starts up here, so I have fond memories.
“It’s certainly one I’ve wanted to win for a long time. Any national championship to me is special, particularly to the people from that country. It’s an honour for me to be the open champion.”
