Justin Rose kept alive his hopes of winning back-to-back US Open titles with a battling first round 72 at Pinehurst.
Despite having the best of the conditions, Rose was four over par after nine holes, but birdied three of the next five before a duffed chip on the eighth cost him a fifth bogey of the day.
"I've got to play some great golf the rest of the week," Rose said after finishing on a two-over-par 72. "I had to do that pretty much no matter whether you shot 66 today or 72. If I shot 66 I wouldn't be here thinking, well, that's won me the tournament. A 72 certainly hasn't lost me the tournament.
"I was telling myself if I get it back to two over and then shoot one under each for the next two days... that's the way I try to break it down.
"I shot two under on the back nine today and got myself back to two over, and even par is within striking distance. If I play well I feel I can get it under par."
The 33-year-old, looking to become the first player since Curtis Strange in 1989 to make a successful title defence, added: "Being a different golf course I never really treated it as being defending champion.
"It was always going to be a new test so I just try to focus on the golf course. I feel like I'm playing pretty free out there. I feel like I'm playing the golf course more aggressively each day."