Japan's Hideki Matsuyama got off to a slow start as he bids to win his third Waste Management Phoenix Open title - while Justin Thomas and Rickie Fowler share the lead.
The American pair both shot clean rounds in Scottsdale, with Thomas carding five birdies across six holes of the back nine to grab a share of the lead.
Fowler holed an eagle putt on the par-5 13th on his way to 64, matched by Harold Varner who also went round in seven-under.
Scotland's Martin Laird is a shot behind, having started his round with a birdie-bogey-eagle, while England's Tyrrell Hatton is tied for 6th on five under.
Matsuyama won the title in 2016 and 2017 and was gunning for a third-straight in 2018 when he was forced to withdraw with a wrist injury.
His round of 68 was enough for joint 27th alongside 12 other players, including partner and defending champion Gary Woodland, and Phil Mickelson who is making a record 30th appearance in the event.
Waterford man Seamus Power is in a race to make the cut after a level-par 71 that featured three birdies and three bogeys.