Brandt Snedeker finished his 6-under-par 66 so early on Saturday that he was able to spend about an hour helping the CBS television crew with commentary.
By the time the third round was over, Snedeker held a one-stroke lead over Dustin Johnson and amateur Jared du Toit of Canada in the RBC Canadian Open at Glen Abbey Golf Club in Oakville, Ontario.
Snedeker holed a seven-foot eagle putt on the final hole and had a 54-hole total of 9-under 207.
"It was a great way to finish, but I didn't expect to be ahead at the end of the day," said Snedeker, who needs some good results to make the United States team for the Ryder Cup at the end of September. "It's important that I make that team.
"I have to get my game in shape and this was a good start. I just have to pull on my experience tomorrow and play well again. There are a lot of guys right there and I will need to play another great round to win."
Du Toit, trying to become the first Canadian to win his national championship since Pat Fletcher in 1954, sank a 40-foot eagle putt on the last hole to complete a 70 and will play in the final twosome with Snedeker on Sunday.
"It feels good," said du Toit, who will be a senior at Arizona State and is playing in his first PGA Tour event. "I've never been here before, but I'm looking forward to it.
"This will be a new type of pressure at atmosphere for me, but I'm just trying to have fun and golf my ball."
Johnson, the U.S. Open champion and second-ranked player in the world, was tied for the lead after each of the first two rounds but needed a 12-foot birdie putt on the 18th hole to shoot 71 and grab his share of second.
Steve Wheatcroft made a 43-foot eagle putt on the last home to card a 64 for the low round of the day, and was two shots back in a tie for fourth with Alex Cejka, who holed a 84-foot birdie bomb on the closing hole.
Martin Laird of Scotland finished at 68 and was another stroke behind in a tie for sixth with Cameron Tringale (69), Matt Kuchar (70), Chad Campbell (70), Ricky Barnes (71) and Jon Rahm (72) of Spain.
Top-ranked Jason Day of Australia, the defending champion, followed his second-round 76 with a 69 and was seven shots down in a tie for 28th.