LOS ANGELES — During a recent practice, Claire Liu sent an easy forehand sailing to the fence beyond the baseline and pressed a palm to her forehead.
“Smile, you’re having fun,” said Chris Tontz, Liu’s coach.
“Am I?” she said with a laugh.
She should be. Liu, 17, is currently the top-ranked junior in the world and the No. 292 player in WTA rankings. In the last three months, Liu has won two titles on the Pro Circuit, a level below the WTA Tour, and become the first American to win the Wimbledon girls’ title since Chanda Rubin in 1992.