Henrik Stenson, Dustin Johnson in Joint Lead at US Open

Henrik Stenson and Dustin Johnson were holding on to their US Open first round joint lead on Thursday after firing 65s in the early play. (Tiger Woods' Woes Continue at US Open)

With the afternoon starters trying to chase down the leading par, the closest was American Ben Martin who was at four under through eight, mainly thanks to an eagle-two at the par-four 12th.

South African Branden Grace was three under at the turn and amateur Brian Campbell was three under after six holes.

Masters champion Jordan Spieth made an indifferent start and was even at the turn as was playing partner Justin Rose.

Tiger Woods, meanwhile, was again struggling and was four over after just eight holes, raising doubts over whether he will make it through to the weekend.

World number one and tournament favourite Rory McIlroy looked dismayed after four bogeys left him with a two over 72.

But but there were smiles on the faces of the two oldest men in the tournament - Colin Montgomerie and Miguel Angel Jimenez after both carded 69.

Patrick Reed was alone in third in the clubhouse after a 66 with fellow American Matt Kuchar a shot further back.