With 98 career PGA Tour starts, Dufner is still looking for his first win.
OAKVILLE, Ontario (AP) -- Jason Dufner played six holes in 1 under Sunday to top the Canadian Open leaderboard before play was washed out because of the latest round of heavy rain and lightning, forcing the tournament to at least a fifth day.
"Instead of reading the grain, you have to read the current out there," said Mike Weir, the Canadian star who had a hole-in-one and was caught up in a confusing rules situation involving his second shot on the 18th hole Saturday.
Dufner, the second-round leader after rounds of 68 and 63 on the saturated Glen Abbey course, had a one-stroke lead over Anthony Kim and Jerry Kelly. Kim was 4 under after nine holes in the third round, and Kelly was 1 under through six.
"None of the players can control what's going on," Dufner said. "I think everybody wants to get out there and play and compete and try to win this golf tournament."
The players are scheduled to resume play at 7:30 a.m. Monday, the first time the tournament has gone past the weekend since 1988. PGA Tour officials still hope to complete four rounds in the event drenched by about 5 inches of rain in four days.
Play began Sunday morning in sunny conditions, but lightning forced the players off the course at 10:15 a.m. After another round of lightning and heavy rain and hours trying to get the layout in shape to resume, play was called for the day at 4:25 p.m.
"We've had some good times in the locker room," Kelly said. "I get up in the kitchen a lot, which I love. Have a good time with all those guys in the kitchen.
"This way you get to know a lot of the players, too. It's time that you're really not grouped together just passing each other, saying hello or eating. You're actually hanging out for hour upon hour. So it's actually a pretty good time in that respect. But it's tough on the golf. It's tough stopping and starting."
Scott Verplank was two strokes back at 12 under along with Retief Goosen, Bob Estes, Peter Tomasulo and Michael Letzig. Verplank, the 2001 winner at Royal Montreal, tied for second behind Ken Green in the 1988 Monday finish at Glen Abbey.
Weir, trying to become the first Canadian winner since Pat Fletcher in 1954, was 9 under -- including a penalty stroke for the infraction at the end of his round Saturday -- with seven holes left in the third round.
Weir's ball moved before he played the shot, but he was unsure whether he had addressed the ball or caused it to move. After calling for a ruling, he replaced the ball in its original location and took a one-stroke penalty.
Before Weir signed his scorecard, the penalty stroke was rescinded after he and the rules committee reviewed video and determined it was inconclusive whether he caused the ball to move. On Sunday, additional video was reviewed, and Weir again assessed himself a one-stroke penalty for causing the ball to move, even though it was still inconclusive whether he addressed the ball.
"Even though I don't think I did, I guess there's that gray-area possibility I could have," Weir said. "So with that, I didn't feel comfortable myself not taking it."
Weir holed a 4-iron shot on the 200-yard fourth hole. The ace was the seventh of the week, the most since the tour began keeping extensive records in 1971. There were five in the 2004 John Deere Classic.
Did he buy a round of drinks for the guys in the locker room?
"I was told that today by a lot of players," Weir said. "So OK. It's good drinking weather right now."