San Francisco - World number one Dustin Johnson fired eight birdies in a seven-under par 64 on Friday to grab a share of the second-round lead alongside rookie Beau Hossler at the Pebble Beach National Pro-Am.
Johnson, playing on the par-71 Monterey Peninsula course, one of three in use for the tournament, had just one bogey as he gained ground on overnight co-leader Hossler.
Hossler, who played the par-72 Spyglass Hill, had five birdies in a five-under 67 that put him on 12-under as well.
The leading duo were two strokes in front of Julian Suri, who carded a four-under 67 at Monterey Peninsula to get to 10-under and Troy Merritt, who shot a five-under 67 at Spyglass Hill.
Johnson, who opened the year with a victory at the Tournament of Champions in Hawaii last month, teed off on the 10th hole at Monterey Peninsula and birdied his first three holes. He followed his lone bogey of the day with back-to-back birdies at 16 and 17, and picked up three more birdies coming in.
"Kind of the same as yesterday," Johnson said. "I just felt like I played really solid, hit a lot of really good shots, hit a lot of good putts and it was a pretty easy day."
Johnson said he's approaching the form that saw him win three straight tournaments early last year before he fell on some stairs and hurt his back as he prepared to tee it up in the Masters.
"The game's really close," Johnson said. "I don't know if it's quite as good as it was during that stretch. That was probably some of the best golf I've played in my career, but parts of the game are just as good."
Five-time major-winner Phil Mickelson, a four-time winner in the tournament that teams amateurs from the world of big business, sports and celebrity with the pros, put himself in the mix for the weekend with a bogey-free 65 at Monterey Peninsula that left him tied for fifth on nine-under par.
"I am having fun," said the 47-year-old American, who is seeking a 43rd US PGA Tour title and his first since the 2013 British Open.
He hit nine of 13 fairways and 15 of 18 greens in regulation but said he expected a tougher challenge when he plays the par-72 Pebble Beach Golf Links on Saturday.
"I think Pebble's a little bit tougher because the greens are a little firmer and smaller," he said "But if you play well, you can birdie and score low on all three (courses)."
World number two Jon Rahm of Spain had five birdies without a bogey in his five-under par 67 at Pebble Beach on Friday. That put him alongside Mickelson in the group of six players sharing fifth place on nine-under, which also included former world number one Jason Day who posted a six-under 65 at Monterey Peninsula.
Northern Ireland star Rory McIlroy, playing the tournament for the first time, was five-under for the tournament through 13 holes of the second round when disaster struck at Monterey Peninsula's driveable par-four fifth -- his 14th hole of the day.
He nearly drove the green and putted his eagle attempt to within 10 feet. But he needed four more putts from there, recording a double-bogey on the hole. He added two more bogeys on the way to a three-over 74.
He was one-under for the tournament, with work to do on Saturday to make the 54-hole cut.
Leading second-round scores on Friday in the US PGA Tour Pebble Beach National Pro-Am on the par-72 Pebble Beach Golf Links, par-71 Monterey Peninsula and par-72 Spyglass Hill courses:
131 - Dustin Johnson 67-64
132 - Beau Hossler 65-67
133 - Julian Suri 66-67
134 - Troy Merritt 67-67
134 - Phil Mickelson 69-65, Jon Rahm (ESP) 67-67, Aaron Wise 65-69, Kevin Streelman 65-69, Jason Day (AUS) 69-65, Steve Stricker 69-65
135 - Tyrone Van Aswegen (RSA) 67-68, Patrick Rodgers 70-65
136 - Chris Stroud 68-68, Will Zalatoris 67-69, Eric Axley 69-67, Peter Malnati 67-69
137 - Paul Casey (ENG) 67-70
137 - Matt Kuchar 66-71, Jason Kokrak 70-67, Jimmy Walker 68-69
138 - Cameron Tringale 70-68, Denny McCarthy 72-66