Dustin Johnson opened up a four-shot lead at the halfway stage of the US Open, as Ian Poulter and Justin Rose faltered late in the round at Shinnecock Hills.

World No 1 Johnson followed up his opening-round 69 with a three-under 67 to set the clubhouse target at four under, with none of the Friday afternoon starters able to join the 2016 champion under par.

Overnight joint-leader Scott Piercy and Charley Hoffman are Johnson’s nearest challengers on level par, with Poulter and Rose part of a group of five a further shot off the pace.

Poulter got within one of Johnson but he triple-bogeyed his penultimate hole – the eighth – and dropped a shot at his last, with Rose also in the group on one over after finishing with back-to-back bogeys.

Tommy Fleetwood and defending champion Brooks Koepka fired matching round-of-the-day 66s to join the group in a tie-for-fourth, with Henrik Stenson also on that score heading into the weekend.

Johnson, beginning on the back nine and in a four-way tie for the lead, holed from 10 feet at the 11th and added another from a similar distance at the 16th to reach the turn in 33.

The 33-year-old failed to get up and down from a greenside bunker to save par at the first but responded by making a 15-foot birdie at the fourth, before moving further ahead by holing a 45-footer at the seventh.

Poulter had made his charge up the leaderboard by following successive gains from the fourth with another from 12 feet at the seventh, only to thin a bunker shot and chunk a chip into thick rough on his way to a seven at the par-four next.

Tiger Woods suffered an early exit despite closing his two-over 72 with back-to-back birdies, while Rory McIlroy joined him on 10 over after posting four birdies on his back nine to end the day level par.

Jordan Spieth threatened to make the cut after posting four consecutive gains on the back nine, only to close with back-to-back blemishes and miss out by a shot.

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(c) Sky News 2018: US Open: Dustin Johnson moves four clear at Shinnecock Hills