Dustin Johnson three strokes off early lead at AT&T Byron Nelson

James Hahn and Ricky Barnes share the lead after the opening round of the AT&T Byron Nelson, where world No 1 Dustin Johnson also made a solid start.

The American both posted a six-under 64 in the calmer morning conditions at TPC Four Seasons, with Johnson three off the pace after shooting a three-under 67 later in the day.

Barnes birdied the first but gave his shot back with a failed up-and-down at the next, before surging up the leaderboard with four gains in a five-hole stretch from the fourth.

Hahn, playing two groups ahead, reached the turn in 32 and added further gains at the 10th and 13th, as Barnes picked up a shot at the 10th and holed a 15-footer at the 14th.

The former US Open runner-up then cancelled out a bogey at the next with a birdie-four at the 16th to get to six under, while Hahn closed his blemish-free card with a 20-foot gain at the last.

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Matt Kuchar birdied two of his final three holes to grab a share of third spot, joining Jhonattan Vegas, Jason Kokrak and Cameron Tringale on four under.

Johnson, looking for a fourth win in six starts, mixed five birdies with two bogeys to sit alongside Brooks Koepka in the group on three under, while Jason Day and Jordan Spieth lie a further stroke adrift.

Ian Poulter birdied his opening three holes but had to settle for a level-par 70, with Masters champion Sergio Garcia in danger of missing the cut following an opening-round 73.

Watch the AT&T Byron Nelson throughout the week live on Sky Sports 4 - your home of golf. Live coverage begins on Friday from 9pm.