San Francisc - World number one Dustin Johnson got off to a hot start, but it was Kevin Streelman and Beau Hossler who shared the first-round lead on seven-under par on Thursday at the Pebble Beach National Pro-Am. 

Streelman had seven birdies without a bogey in his 65 at par-72 Spyglass Hill, one of three courses in use for the tournament. Hossler nabbed seven birdies at par-72 Pebble Beach Golf Links. 

Matt Kuchar and Julian Suri were in a three-way tie for third after posting matching 66s at Spyglass Hill, with Aaron Mise also getting to six-under at the par-71 Monterey Peninsula. 

"Getting out first was nice," said Streelman, a two-time winner on the US PGA Tour who hit 12 of 14 fairways and 11 of 18 greens - and managed to get up and down at all seven of the greens he missed. "Drove it nice and put it on the greens and made a lot of putts." 

Hossler, 22, said his day was "for the most part stress-free". 

"I hit a lot of greens, had a lot of pretty good looks at birdie," Hossler said. "I stuck to a relatively conservative game plan but was able to get a couple of long putts to go in at the end." 

Johnson, winner of the event in 2009 and 2010, birdied five of his first 11 holes at Spyglass, finishing with six birdies and a bogey in a five-under 67 that left him two shots off the lead. 

The world number one, playing his first US PGA Tour event since winning the Tournament of Champions last month, played alongside defending champion Jordan Spieth, who had one birdie and one bogey in an even par 72 that left him well off the pace in a tie for 98th place. 

Northern Ireland's world number eight Rory McIlroy had six birdies and two bogeys in his four-under 68 at Spyglass. 

McIlroy is making his first appearance in the tournament in which celebrity and corporate executive amateurs play alongside the pros. 

He teed it up with his father, Gerry McIlroy, and called the experience "awesome". 

They played in a group with five-time major-winner Phil Mickelson, who made the turn two-over after three bogeys and a birdie on the front nine, but birdied five of his last eight en route to a three-under 69. 

"It was a nice way to finish after not getting off to a great start," said Mickelson. "I was able to get back in it." 

Celebrity participants like actor Bill Murray, ice hockey great Wayne Gretzky, Green Bay Packers quarterback Aaron Rodgers and World Series-winning Houston Astros pitcher Justin Verlander give the Pro-Am it's unique, festive flavour. 

But plenty of serious golf business remains, including world number two Jon Rahm's bid to overtake Johnson atop the world rankings. 

Spain's Rahm played Monterey Peninsula on Thursday and birdied his last three holes to sign for a four-under par 67.

Leading first-round scores on Thursday 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:

7-under par

65 - Kevin Streelman, Beau Hossler

6-under par

65 - Aaron Wise

66 - Matt Kuchar, Julian Suri

5-under par

66 - Cameron Percy, Patrick Cantlay

67 - Chez Reavie, Troy Merritt, Will Zalatoris, Rob Oppenheim, Paul Casey (ENG) Dustin Johnson, Keith Mitchell, Dou Zecheng (CHN)

4-under par

67 - Shane Lowry (IRL), Jon Rahm (ESP), Charley Hoffman, Talor Gooch, Chris Kirk, Tyrone Van Aswegen (RSA), Peter Malnati, Jonas Blixt (SWE)

68 - Rory McIlroy (NIR), Chris Stroud, Stephan Jaeger (GER), Jimmy Walker, Branden Grace (RSA), Ted Potter Jr, Ben Crane, Zhang Xinjun (CHN)