(Photo credit: Geoff Burke-Imagn Images)
Germany's Alexander Zverev, the only two-time champion in the Nitto ATP Finals field, opened his play in the event with a 6-4, 6-4 victory over Russia's Andrey Rublev on Monday in Turin, Italy.
Zverev, the event's second seed, and Rublev, the eighth seed, began round-robin play in the John Newcombe Group.
In the other match on Monday, also in the Newcombe Group, sixth-seeded Casp
