Rickie Fowler fired a blemish-free 65 to grab the early advantage at the US Open, as Rory McIlroy made a nightmare start to his week at Erin Hills.
Fowler struck seven birdies in benign conditions in Wisconsin to finish one ahead of Paul Casey and Xander Schauffele, while McIlroy faces a battle to make the cut after an erratic display off the tee.
The world No 2 posted two double bogeys on the back nine on his way to a six-over 78, with Jason Day a further stroke back and defending champion Dustin Johnson stuttering to an opening-round 75.
Beginning on the back nine, Fowler birdied three of his opening five holes and grabbed the outright advantage with a hat-trick of gains around the turn.
Fowler rolled in from 12 feet at the seventh to complete a bogey-free card and move two clear, only for Casey halved his advantage as the pick of the afternoon starters.
The Englishman chipped in to eagle the first on his way to a front-nine 32 and cancelled out a blemish at the 10th with gains at the 11th and 15th, before picking up a shot at the last to close a six-under 66.
Schauffele threatened the lead late in the day and moved within one of Fowler with three birdies in a four-hole stretch, before missing a 10-foot putt on his final hole for a share of the advantage.
Tommy Fleetwood heads the European interest and a bogey-free 67 saw him join American pair Brooks Koepka and Brian Harman two off the pace, with Patrick Reed one of four players on four under.
Andrew “Beef” Johnston and Lee Westwood lie four off the pace, as Sergio Garcia eagled his opening hole on his way to a two-under 70.
Only six players finished further down the leaderboard than McIlroy, who reached the turn in level-par but followed bogeys at the 11th and 13th with double-bogeys in two of his final four holes.
Day was one of those as he posted two triple-bogeys on his way to a seven-over 79, while Johnson and playing partner Jordan Spieth were left to rue poor putting displays