Hunter Mahan, the leader after 36 holes, withdrew from the PGA Canadian Open on Saturday after learning that his wife was preparing to give birth to their first child.H

The 31-year-old American was on the practice range at Glen Abbey after his start to the third round was delayed by a storm in the area when he received a call on his cell phone.

Moments later, Mahan pulled out and left the course for the Toronto airport, set to make a 2 1/2-hour flight to Dallas to be with his wife, Candi, after she went into labor. She was expected to give birth in three weeks.

The situation evoked memories of Phil Mickelson at the 1998 US Open at Pinehurst when the US left-hander, who won last week's British Open, was playing with a cell phone in his bag awaiting news that his wife Amy was going into labor. Mickelson contended for the title but finished second and became a father the next day.

Mahan had fired a 67 in the first round and a 64 in the second to stand atop the leaderboard at 13-under par 131 for 36 holes.

He was seeking the sixth US PGA Tour victory of his career and his first of the season. His best showing this year was a runner-up effort at the World Golf Championships Match-Play Championship. Since then, his only top-10 showings came at majors, a share of fourth at the US Open and ninth at the British Open.

Mahan's withdrawal left compatriot John Merrick, set to tee off alone in what was to have been the final group and sharing the lead at 11-under with fellow American Dustin Johnson, who completed a third-round 63 just as Mahan was departing to stand on 11-under 205 after 54 holes.

"Hopefully Hunter can get back and everything is OK," Merrick said. "It's pretty strange this happening. It is unusual to play by yourself in the last group."

Johnson had played alongside Mahan in the first two rounds.

"It's a good thing he is going. He's having his first child. There's no reason he wouldn't go," Johnson said. "You never want to see someone withdraw but there is a really good reason.

"It's unfortunate he had to go. He was playing well. It was going to be tough to catch him the way he was playing."

Johnson does like his chances, however, now that Mahan is gone.

"I'm in a good position for tomorrow," Johnson said. "I'm glad to be hitting the ball well. I'm playing a little better. I'm hitting the ball straighter, controling my distance a little better."