Phil Mickelson has insisted that he is in a strong position after day one of the US Open at Chambers Bay.

The left-hander shot an opening round-score of 69, which leaves him four shots off co-leaders Dustin Johnson and Henrik Stenson, who sit on five-under-par.

Many players have found putting on the course difficult, including world number one Rory McIlroy, but Mickelson has labelled it a "fair test".

He told reporters: "I played well. I had a really nice round going and then made bogey on 13 and 14. I think the 13th is the hardest approach shot into the green. I did not leave myself the best shot and was way too far back and then made a good bogey on the next. [But] no complaints. I'm under par in the first round of the US Open and I am pretty pleased.

"I thought it was a very fair test. The set-up was good. I think everyone in the field is going to struggle with three to eight-foot putts when they are downhill because you can't hit it hard enough to hold the line and there is a lot of wiggle.

"The first round was the round I was going to be most nervous at, getting started. You don't want to have to fight to come back all the time. You want to get off to a solid start around par. I'm very pleased with the way the round went."

The US Open is the only Major Mickelson is yet to win, having finished as runner-up on six occasions.