Martin Kaymer has admitted that he was surprised by the opportunity to post low scores on the first day of the US Open at Pinehurst.
The former world number one leads by three shots after carding a five-under-par 65 on Thursday, but he is expecting the course officials to make it tougher for the players over the next three days.
"If you shoot anything under par or level par on that golf course, it's good," Kaymer told members of the press.
"I watched some golf this morning and I was very surprised how playable it was because yesterday I played in the morning and it was very firm so they must have put a lot of water on the greens last night.
"Usually, it only gets more difficult and more firmer and faster."
Kaymer is looking for a second Major victory to add to his success in the USPGA Championship in 2010.
