The first round of the 2012 U.S. Open has commenced at the Olympic Club in San Francisco. The action can be watched live on ESPN from 12 p.m. ET and will remain on that channel until 3 p.m. ET. From then on coverage will switch to NBC from 3 p.m. through 5 p.m., at which point it will switch back over to ESPN and remain on that network until 10 p.m. close of play.