<p>Turin: Stefanos Tsitsipas retired after just three games of his Green Group clash against Holger Rune at the ATP Finals on Tuesday, handing the Danish debutant his first victory in the event.</p><p>Greek world number six Tsitsipas looked uncomfortable as he trailed 2-1 and after consulting with a doctor at the changeover he decided that he could not continue.</p><p>Tsitsipas, who lost in straight sets to Jannik Sinner in his opening match on Sunday, appeared to be troubled by a back problem and left the court to a few jeers from the large crowd inside the Pala Alpitour.</p>.Jannik Sinner dispatches Stefanos Tsitsipas in dream start to ATP Finals.<p>As a consolation for the ticket holders, alternates Taylor Fritz and Hubert Hurkacz were due on court to play an exhibition match, although it will not count for the tournament.</p><p>"For sure it was very unfortunate," 20-year-old Rune said. "Even in the first service game you could see he wasn't serving anywhere near full like he can, I knew something was off."</p><p>After only 15 minutes on court, Rune said it was impossible to take anything from the match, although he will go in to his clash with Sinner in confident mood after pushing Djokovic close in a near three-hour duel on Sunday.</p><p>"I have never played that well in my life and lost," Rune said on court. "That's how good Novak is."</p><p>Djokovic, who is assured of finishing year-end world number one for an eighth time, faces Sinner later. </p>
<p>Turin: Stefanos Tsitsipas retired after just three games of his Green Group clash against Holger Rune at the ATP Finals on Tuesday, handing the Danish debutant his first victory in the event.</p><p>Greek world number six Tsitsipas looked uncomfortable as he trailed 2-1 and after consulting with a doctor at the changeover he decided that he could not continue.</p><p>Tsitsipas, who lost in straight sets to Jannik Sinner in his opening match on Sunday, appeared to be troubled by a back problem and left the court to a few jeers from the large crowd inside the Pala Alpitour.</p>.Jannik Sinner dispatches Stefanos Tsitsipas in dream start to ATP Finals.<p>As a consolation for the ticket holders, alternates Taylor Fritz and Hubert Hurkacz were due on court to play an exhibition match, although it will not count for the tournament.</p><p>"For sure it was very unfortunate," 20-year-old Rune said. "Even in the first service game you could see he wasn't serving anywhere near full like he can, I knew something was off."</p><p>After only 15 minutes on court, Rune said it was impossible to take anything from the match, although he will go in to his clash with Sinner in confident mood after pushing Djokovic close in a near three-hour duel on Sunday.</p><p>"I have never played that well in my life and lost," Rune said on court. "That's how good Novak is."</p><p>Djokovic, who is assured of finishing year-end world number one for an eighth time, faces Sinner later. </p>