New-look US Open course challenges golf's best

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Rickie Fowler of the US hits a shot from a greenside bunker as golfers play a green during a practice round prior to the start of the 115th US Open Championship at Chambers Bay in University Place, Washington Satae on June 17, 2015

Tacoma (United States) (AFP) - The 115th US Open was set to tee off early Thursday on an untested Chambers Bay layout that has left the world's top golfers scratching their heads over how best to play it.

World number one Rory McIlroy is seeking a fifth major title, Masters champion Jordan Spieth aims to make it halfway to the fabled calender-year Grand Slam and crowd favourite Phil Mickelson is desperate to finally win a US Open, after six runner-up finishes, and in so doing complete his career Grand Slam.