Dean Wilson watches his tee shot in the pouring rain on the eighth hole during the third round of the Canadian Open on Saturday. (Frank Gunn/Canadian Press)

Unsure if he'd even get a spot in the RBC Canadian Open at the start of the week, Dean Wilson is now just 18 holes away from winning the third oldest national championship in golf.

Wilson shot a 5-under 65 at St. George's Golf and Country Club in Toronto on Saturday to put some distance between himself and a crowded leaderboard.

His 195 total is four shots better than Carl Pettersson (60), Bob Estes (66) and Tim Clark (68).

Bryce Molder (63), Trevor Immelman (65), Kevin Sutherland (65) and Brock Mackenzie (68) were in a group five shots back.

Hawaiian-born Wilson was Mike Weir's college roommate and said earlier in the week that organizers gave him a late exemption into the event at the urging of the Canadian lefty.

"I'm pretty sure [Weir] had a big hand in it," Wilson said Saturday. "When they're going to hand out sponsor exemptions and they've got a chance of giving it to a John Daly or a Dean Wilson, they're going to lean towards John Daly.

"I'm just fortunate to be in [the tournament]."

He put together a steady round in intermittent rain that left large puddles on the rolling fairways at St. George's. Wilson pulled ahead of Clark with consecutive birdies on Nos. 9 to 11, taking advantage of the easiest stretch on the course.

The 40-year-old is looking to become the third straight unlikely champion of the event, following Chez Reavie (2008) and Nathan Green (2009). Wilson currently sits 522nd in the world ranking — 398 spots behind Clark — and has just one career PGA Tour victory to his name.

It's the first time Wilson has ever held the 54-hole lead on the PGA Tour. He's experienced plenty of struggles in recent years and doesn't hold full-time playing privileges — a humbling experience for a veteran who won the 2006 International and six professional events in Japan.

"I'm a little more appreciative of getting in tournaments and playing and being out here," said Wilson. "That time away makes you think about what you don't have."

Top Canadians

Adam Hadwin (70) of Abbotsford, B.C., and Jon Mills (66) of Oshawa, Ont., were both nine shots out of the lead and tied for low Canadian. Calgary's Stephen Ames (73) was four behind them.

It's been a breakthrough week for the 22-year-old Hadwin, who got into his first PGA Tour event because of his high standing on the Canadian Tour.

"That crowd roar at nine for my eagle — I was shaking," he said. "I could feel it all the way in my inner-most bones."

The rain was more of a factor on Hadwin's back nine, and he was pleased to close out with two pars.

"I was trying to be aggressive, maybe too aggressive on a couple of shots, but I really felt like I could have played well and maybe pushed it to double-digits today," he said.

Mills, meanwhile, had a run of four birdies over five holes on the front nine. He was also pleased to be in the mix after three rounds.

"This is obviously nice to play well in front of a hometown crowd," he said. "And you know, it's been a couple of years since I've been on the tour and I was really looking forward to playing this week.

"I'm just going to kind of go with what got me here and just kind of have fun with it."

Ames is playing his first competitive event in a month. He seemed satisfied, given the weather and his recent break.

"I'm just trying to get it back to where I can continue playing, and work from then on to the other events," Ames said. "So in some respects that's what you try to do. You get four rounds under your belt, which is what I'm doing here now and you get some playing time in there, and you work on your golf swing."

Pettersson was in the third group off the tee and flirted with golf's magic number before the rain started.

Clark and a couple other players came out to the 18th green and watched as the Swede narrowly missed a 30-foot putt that would have made him the fifth man in PGA Tour history to shoot 59.

Afterwards, he had a little trouble recounting exactly where he picked up all of his shots.

"You sort of get in your own little zone and just keep going," said Pettersson. "You don't really want to think about it because then your mind works against you. I just try to blank everything out.

"In the moment, it's just kind of a blur."

Course record

His 60 is the lowest score ever shot at the 101-year-old event and established a new course record at St. George's. Six players in Canadian Open history have signed for a 62, including Brent Delahoussaye on Thursday and Sutherland on Friday.

Pettersson's round included two eagles, seven birdies, one bogey and eight pars.

"Obviously I'm thrilled to shoot 60," he said. "But to shoot 59, I don't know how many chances you're going to get in your lifetime. … I would have loved to have seen that putt go in."

Pettersson felt like he was on borrowed time simply by getting the chance to play here on the weekend.

"I thought I was going to miss the cut yesterday," he said. "We got finished with the round and it was right on borderline, and me and Jay Williamson were actually watching the computer to see if we were going to make the cut.

"We had a few Canadian beers in there and that settled me down, I think. Maybe that's what did it."