With the overnight leader out of the picture, Brandt Snedeker fired a 9-under-par 63 on Saturday to jump ahead by a stroke through three rounds of the Canadian Open.

Shortly before he was set to tee off, second-round leader Hunter Mahan withdrew to be with his wife Kandi, who went into labor with their first child.

"I received exciting news a short time ago that my wife Kandi has gone into labor with our first child," said Mahan, who was coming off back-to-back top-10 finishes at the last two majors. "As a result, I have withdrawn from the RBC Canadian Open to return to Dallas. I would like to extend my very sincere gratitude and appreciation to RBC and the RBC Canadian Open."

When Mahan withdrew, John Merrick found himself in the lead, playing alone in the final group. Merrick then endured an 80-minute weather delay before he teed off. When he finally hit the course, the results were not ideal, as Merrick shot even-par 72 and dropped into a tie for fifth place.

Snedeker went bogey-free at Glen Abbey Golf Club and moved to 14-under-par 202 through 54 holes, one stroke better than David Lingmerth, who eagled his final hole to highlight his third-round 65.

"I looked at my caddie, and I go, 'what's going on?' He goes: 'I think Hunter had to leave because Kandi went into labor," said Snedeker, who learned the news while on the seventh tee. "That just kind of left the tournament wide open. Hunter was going to be hard to catch because he was playing so good, and the way drives the golf ball on this golf course he was going to play really well on the weekend. For me to catch him, I knew I was going to have to shoot something really low."

Matt Kuchar, a two-time PGA Tour winner this season, shot 64 and jumped into a share of third place alongside Jason Bohn (66) at 12-under.

Dustin Johnson, who played with Mahan the first two days, fired a 63 and moved into a tie for fifth place at minus-11. He sits alongside Merrick, Charley Hoffman (67), Kyle Stanley (66) and Greg Owen (67).

Looking for his first win since the season-opening Hyundai Tournament of Champions, Johnson set the early pace by going bogey-free on Saturday. The big-hitter had seven birdies and capped his 9-under round with an eagle at the par-5 last.

But Snedeker, looking increasingly like the golfer who recorded consecutive runner-ups and a win at Pebble Beach earlier this season before being sidelined by a rib injury, methodically worked his way to the top.

The five-time PGA Tour winner opened with two birdies in his first three holes and later turned the trick in succession from both the fifth and eighth to turn in 29.

After a par at the 10th, Snedeker rolled home a 14-foot birdie putt at No. 11 to take the lead at 12-under. He never looked back, adding birdies at Nos. 13 and 16, then parring the 17th and 18th to take a 1-stroke advantage into the final round.

"I think 18-, 19-, 20-under par is going to be the score to get to, and I'm going to try to get past that," he said. "It's one of those courses where you know you've got to make birdies. It's actually kind of a comforting feeling because you know you have to be aggressive all day long."

NOTES: Snedeker tied for eighth at AT&T National and shared 11th at the British Open Championship in his previous two starts ... Mahan hasn't won since earning his fifth tour win at the 2012 Houston Open ... The top Canadian after three rounds is David Hearn, who is tied for 39th at 5-under- par 211 ... Defending champion Scott Piercy is tied for 67th at 1-under-par 215 through 54 holes.