Adam Hadwin of Canada is the leader heading into the second round of the U.S. Open. Hadwin ran off three straight birdies at the end of the front nine and only dropped one shot on the back nine of The Country Club for a 66. He leads by one shot over five players, including Rory McIlroy.  Hadwin got into the field as an alternate.  He walked off Thursday with a 4-under 66 for his best score in 63 rounds at major championships and a 1-shot lead over Rory McIlroy and four others at 67: Callum Tarren of England, David Lingmerth of Sweden, MJ Daffue of South Africa and Joel Dahmen.