Billy Horschel has revealed that patience was crucial as he moved to the top of the US Open leaderboard alongside Phil Mickelson at the end of day two.
The American hit all 18 greens in regulation on his way to a round of 67, three-under-par for the course at the Merion Golf Club.
The 26-year-old told Sky Sports News: "It was a great day. Four birdies at a US Open. I'll take it. I wish I had a couple more, though.
"I didn't know I hit every green until I walked off 18. It's a cool thing, but it's not the first time I've hit all 18 greens. I've done it plenty of times in my career. Obviously it's at a US Open, but I think the softness of the greens helped that.
"Everything seems good. I've just got to stay patient and keep committing and executing every shot and I'll be okay on Sunday. Patience is something that has always been a struggle for me, but I'm doing a really good job of it this week, staying patient and just taking what's in front of me."
Horschel failed to make the cut in his only previous appearance at the tournament, when he competed as an amateur in 2006.