There was much toil on the opening day of the US Open at the Olympic Club in San Francisco, with only six players scoring under par.

Americans dominate the top 10, with 27-year-old Michael Thompson topping the leaderboard after shooting a magnificent four-under 66 in the morning.

That score was good enough to earn him the honour of overnight leader, heading a clutch of players lurking three shots back.

Tiger Woods is one of those chasing after a patient round of 69, in which he only dropped two shots on a course that was set up for maximum difficulty.

David Toms joins him on one-under, as does Nick Watney, who shot an astonishing albatross at the 17th hole, which had dragged him back to even par.

Justin Rose and Graeme McDowell have made sure that Britain is represented on the leaderboard after day one, as they too shot 69 to leave themselves on one-under, while Ian Poulter came in even par.

Lee Westwood clubbed a three-over 73, but scrambled well to get up and down during the back nine and keep himself in contention come the second round.

However, his partners for the round, Luke Donald and Rory McIlroy, were not as successful in the art of damage limitation, carding nine-over and seven-over respectively.

Masters champion Bubba Watson will also find it difficult to make tomorrow's cut after a round of eight-over, while Phil Mickelson struggled to card six-over for the day.