He’s got a stranglehold on the No. 1 ranking. He’s unbeaten this week and hasn’t dropped a set. And his home Italian fans can’t get enough of him. Things couldn’t get much better for Jannik Sinner at the ATP Finals so far — despite an ongoing doping case that likely won't be decided until early next year.

Taylor Fritz, the U.S. Open finalist who lost to Sinner in New York, was also drawn in the Italian’s group alongside Australian Alex De Minaur, making his ATP Tour Finals debut; Casper Ruud and Andrey Rublev, who qualified as world No. 9 after Novak Djokovic withdrew, rounded out the second group.

Sinner won his opening two matches and plays Daniil Medvedev later. Last year, Sinner lost the final to Novak Djokovic, who pulled out injured this year. Fritz also has two wins, while Medvedev is still in contention and could get to two wins by beating ...