Second round leaders (left to right) Jordan Spieth (2nd), Derek Ernst (3rd) and Chris Williams (1st) wait to tee off in the third round Thursday.

Emiliano Grillo, 17, of Resistencia, Argentina, tees off in Thursday's third round.

Top Amateur golfers Andrew Yun, 20, of Chandler, Ariz., and John Hahn, 22, of Hudson, Ohio, talk on the tee before beginning their third round Thursday.