Jannik Sinner is the reigning Australian Open and Wimbledon champion
Jannik Sinner drove Alexander Zverev to distraction with a composed performance to reach the knockout stages of the ATP Finals.
The Italian second seed maintained his bid for the year-end world number one ranking with a 6-4 6-3 win over third seed Zverev.
Sinner saved all seven break points he faced with his immense serve, with one ace leaving his 28-year-old German opponent biting his racquet in frustration.
The four-time major champion, 24, is the first player to reach the semi-finals in Turin.
