Golf-USGA chief says Open test could be a mind game

June 11 (Reuters) - The U.S. Open is the toughest test in major championship golf, and United States Golf Association chief Mike Davis says this year's examination at Chambers Bay will be as much mental as physical.

"It's going to require that the players think on their feet a little bit more than they would normally," USGA executive director Davis told Reuters in an interview.

"Players are not only going to have to execute good shots and think well, but they're going to have to manage how they play during the round."

The rolling Washington State course designed by Robert Trent Jones Jr., set along Puget Sound on land formerly used as a rock quarry and gravel mine, has been molded into a…