American youngster Sloane Stephens has appointed Paul Annacone as her new coach after a trial in Los Angeles last month.
The 20-year-old announced herself on the world stage last year when she defeated Serena Williams en route to the last four of the Australia Open.
Stephens, ranked 12 by the WTA, has sought the expertise of Annacone, who has worked with Pete Sampras, Tim Henman and Roger Federer, despite him never having coached a female player.
Annacone split with Federer in October after nearly three-and-a-half years together.
"That is a terrific opportunity," he told USA Today. "I'm going to have to get comfortable with it and understand the dynamics. She's going to have to understand me.
"It's about buying into a philosophy which takes more than just being business partners.
"Look, it's not like you're dealing with a 20-year-old kid that hasn't done anything. She's ranked 11 or 12 in the world. She knows how to be successful. Now it's about moving on from that foundation."
Stephens made four semi-finals last season but is still waiting for her first appearance in a final.
