U.S. Open Round 1 grades

— -- PINEHURST, N.C. -- Pinehurst No. 2 was hard for everybody on Thursday. At times, it was difficult to tell the seasoned major champions from the teenaged competitors. But for the most part, these top-15 players in the official world ranking played some very solid golf.

These grades reflect the difficulty of the course and the grit these players demonstrated throughout their rounds.

None of them produced A work, but neither did any of them earn an F. Pinehurst No. 2 was a tough test, and these players have plenty of work to do on Friday and the weekend to improve their grades.

With a packed leaderboard and the margin for error so slim, any of them could easily be A students by the end of the week and perhaps even the 2014 U.S. Open champion.