Bill Haas grabbed the lead after day one of the Waste Management Phoenix Open in Phoenix, Arizona thanks to a seven-under-par 64.
The American has been struggling for form but his impressive afternoon lap at a crowd-packed TPC Scottsdale ensured a two-shot lead over fellow Americans Rickie Fowler, Billy Horschel, Brydon DeChambeau, Chesson Hadley and Chris Kirk.
World number two Jon Rahm, who went to the local Arizona State University, is a further stroke back after a four-under 67 but Open champion Jordan Spieth struggled to a one-over 72. Of the other big games, two-time defending champion Hideki Matsuyama fired a two-under 69 and Justin Thomas a 68.
Six-time PGA Tour winner Haas didn't have a single bogey on his card and birdied three of the four par 3s. The highlight was an eagle three at the 15th.
Haas said: I've been struggling, so just kind of practising, working hard and trying to figure something out. The putter was hot the first nine holes. One of those days where they went in for me so hopefully it will be one of those weeks.
"I like playing in the desert, I love the turf, I love the grass, the greens are going to get firmer and firmer. I think it will put an emphasis on the driver, if you can drive it in the fairway, I still think you'll see guys shoot good scores. But if the wind stays down like this in perfect conditions, it's fun golf."
Fowler, who missed the cut at Torrey Pines last week, said later: "I love playing here. Managed the mistakes properly, made some good putts.
"Looking forward to getting kind of back in the mix after not being around for the weekend last week and off to a good start. Obviously you can't win it the first couple days, but you can obviously take yourself out of it."
Fowler is 1000/1 to win the Waste Management Phoenix Open, with Rahm 1000/1.
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