There are new challenges for the world No. 2 on the eve of the U.S. Open, Bob Harig writes. Also: Joaquin Niemann seeks major success and Oakmont's final field.

The US Open is one of the hardest tests in golf, and at Oakmont, it’ll be even tougher. A star-studded field will assemble in Pennsylvania later this month for the 125th playing of the famous ...