NEW YORK - 3 SETTEMBRE 2016: La campionessa del Grande Slam Serena Williams degli Stati Uniti in azione durante la sua terza partita agli US Open 2016 al Billie Jean King National Tennis Center di New York - Foto e immagini stock

NEW YORK - SEPTEMBER 5, 2016: Grand Slam champion Serena Williams of United States in action during her round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 5, 2016: Grand Slam champion Serena Williams of United States in action during her round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 5, 2016: Grand Slam champion Serena Williams of United States in action during her round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 2, 2018: 23-time Grand Slam champion Serena Williams in action during her 2018 US Open round of 16 match at Billie Jean King National Tennis Center

NEW YORK - SEPTEMBER 5, 2016: Grand Slam champion Serena Williams of United States in action during her round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 3, 2016: Grand Slam champion Serena Williams of United States in action during her round three match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 5, 2016: Grand Slam champion Serena Williams of United States in action during her round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 5, 2016: Grand Slam champion Serena Williams of United States in action during her round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 5, 2016: Grand Slam champion Serena Williams of United States in action during her round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 3, 2016: Grand Slam champion Serena Williams of United States in action during her round three match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 3, 2016: Grand Slam champion Serena Williams of United States in action during her round three match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 5, 2016: Grand Slam champion Serena Williams of United States in action during her round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 5, 2016: Grand Slam champion Serena Williams of United States in action during her round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 5, 2016: Grand Slam champion Serena Williams of United States in action during her round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 3, 2016: Grand Slam champion Serena Williams of United States in action during her round three match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 5, 2016: Grand Slam champion Serena Williams of United States in action during her round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 5, 2016: Grand Slam champion Serena Williams of United States in action during her round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 3, 2016: Grand Slam champion Serena Williams of United States in action during her round three match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 3, 2016: Grand Slam champion Serena Williams of United States in action during her round three match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 3, 2016: Grand Slam champion Serena Williams of United States in action during her round three match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 3, 2016: Grand Slam champion Serena Williams of United States in action during her round three match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 5, 2016: Grand Slam champion Serena Williams of United States in action during her round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 5, 2016: Grand Slam champion Serena Williams of United States in action during her round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 5, 2016: Grand Slam champion Serena Williams of United States in action during her round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 2, 2018: 23-time Grand Slam champion Serena Williams in action during her 2018 US Open round of 16 match at Billie Jean King National Tennis Center

NEW YORK - SEPTEMBER 3, 2016: Grand Slam champion Serena Williams of United States in action during her round three match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 3, 2016: Grand Slam champion Serena Williams of United States in action during her round three match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 3, 2016: Grand Slam champion Serena Williams of United States in action during her round three match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 5, 2016: Grand Slam champion Serena Williams of United States in action during her round four match at US Open 2016 at Billie Jean King National Tennis Center in New York

NEW YORK - SEPTEMBER 2, 2018: 23-time Grand Slam champion Serena Williams in action during her 2018 US Open round of 16 match at Billie Jean King National Tennis Center