(Reuters) - World number one and twice winner Dustin Johnson birdied five of his first 11 holes to sit two strokes behind the opening-round leaders on Thursday at the AT&T Pebble Beach Pro-Am on the Monterey Peninsula in California.
Johnson, competing in his first PGA Tour event since his runaway victory in Kapalua last month, carded a five-under-par 67 at Spyglass Hill, which is considered the toughest of the three venues being used for this week's event.
That left Johnson, who mixed six birdies with a bogey, in a share of sixth place and two shots behind first round leaders and fellow Americans Kevin Streelman and Beau Hossler.
Johnson, who won the event in 2009 and 2010, was paired with defending champion Jordan Spieth, who offset a birdie at the par-four third with a bogey two holes later for an even-par 72 that left him well behind the co-leaders in a tie for 98th.
World number eight Rory McIlroy (68) and five-times major winner Phil Mickelson (69) went off together at Spyglass Hill, and while they finished a stroke apart they could not have arrived at their scores in much different fashion.
Northern Irishman McIlroy was more steady with three birdies and a bogey on both his front and back nine while Mickelson overcame a rough start that included three bogeys and a birdie on his first seven holes with a strong finish in which he birdied five of his final eight holes.
World number two Jon Rahm, playing at Monterey Peninsula, capped his round in style with three consecutive birdies for a four-under 67. Australian world number 10 Jason Day was also in the mix after carding a three-under-par 69 at Spyglass Hill.
The event, which features a 54-hole cut before the final round is contested at Pebble Beach, is wildly popular given the celebrities that compete alongside some of golf's biggest names.
Among the non-golf celebrities competing this week are actor Bill Murray, Justin Verlander of the World Series champion Houston Astros, Canadian ice hockey great Wayne Gretzky and Green Bay Packers quarterback Aaron Rodgers.
(Reporting by Frank Pingue in Toronto; Editing by Greg Stutchbury)