Los Angeles - Justin Thomas drained four consecutive birdies to post a seven-under 64 and grab a share of the first round lead at the PGA Tour's Phoenix Open on Thursday.
Thomas, who began on the back nine, birdied the last hole of his front nine and then added three straight to begin the back. He also had six birdies in seven holes during the middle of his round to finish in a tie with fellow Americans Rickie Fowler and Harold Varner.
"It was very, very hard to get the balls close to the pin early in the round," said the nine-time PGA Tour winner Thomas.
"But I just continued to try to stay patient and was driving it well to where I had wedges and I made some very low-stress birdies."
Thomas, who was one of the pre-tournament favourites, tied for 17th last year. He also missed the cut twice in this event.
Fowler eagled the par-five 13th as part of a four-under score for his first eight holes, while Varner caught the leaders with three birdies on his final six holes.
J.T. Poston and Scotland's Martin Laird are both one shot back after shooting 65s.
The Phoenix Open is the only event on the Tour's west coast swing that doesn't take place in California.
The tournament has finished in a playoff each of the past three years, with Japan's Hideki Matsuyama winning two of those.
While Tiger Woods isn't making an appearance, the field is still strong and features 10 of the top 30 players in the world.
There will be plenty to sort out in the second round as 38 golfers are within four shots of the leaders.
Three-time tournament champion Phil Mickelson shot a three-under 68. With his 30th start in the event, he broke a record previously shared by Gene Littler, Jerry Barber and Australia's Jim Ferrier.
Mickelson, who attended nearby Arizona State University on a golf scholarship, is seeking his 500th official cut on the Tour.
"I shot three-under and it's an okay start. And to birdie the last feels good too, so it was a good way to finish," said Mickelson.
Organisers put Mickelson, Matsuyama and defending champ Gary Woodland together for the first two rounds as the trio have won this event a combined half-dozen times, including the past three years.
Matsuyama shot a 68, and Woodland is at three under, aided by a burst of three straight birdies on the back nine.
He was forced to withdraw last year in the opening round with a wrist injury that eventually saw him miss six weeks of the season.
Leading first round scores on Thursday in the PGA Tour's Phoenix Open at the TPC Scottsdale course (par-72; USA unless stated):
64 - Justin Thomas, Rickie Fowler, Harold Varner
65 - Martin Laird (SCO), J.T. Poston
66 - Tyrrell Hatton (ENG), An Byeong-Hun (KOR), Bubba Watson, Scott Piercy, Charley Hoffman
67 - Emiliano Grillo (ARG), Cameron Smith (AUS), David Hearn (CAN), Jon Rahm (ESP), Branden Grace (RSA), Webb Simpson, Andrew Landry, Matt Kuchar, Nick Watney, Brian Gay, Trey Mullinax, Tom Hoge, John Huh, Xander Schauffele, Ollie Schniederjans