Stefanos Tsitsipas fights back to overcome Dominic Thiem and secure ATP Finals

• Greek becomes youngest winner of event since 2001
• The 21-year-old wins 6-7 (6), 6-2, 7-6 (4)Three years ago, Stefanos Tsitsipas arrived in London as a wide-eyed teenager, happy to offer his services as a hitting partner for Dominic Thiem, whom he knew a little. They got to know each other a lot better on Sunday night, spending two hours and 35 minutes together in front of a capacity crowd here as the 21-year-old Greek became the youngest winner of the ATP Tour Finals since 2001.He