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From next season, seven of the nine ATP Masters 1000 events will be held across 12 days.
Bolelli and Vavassori, the fourth seeds, dominated from the outset.
Sinner, Zverev, four-time Grand Slam winner Carlos Alcaraz, former US Open champion Daniil Medvedev and American Taylor Fritz have booked their spots at the ATP Finals.
The season-ending tournament will be held at Turin from November 10-17.
The 20-year-old Alcaraz will need to beat Medvedev in his final group game on Friday.
The earlier Green Group clash was a non-event as Stefanos Tsitsipas retired injured against Holger Rune.
Rublev, ranked fifth in the world, began to despair after losing the first set and failed to put up much of a fight in the second.
Jannik Sinner made a dream start in front of his home crowd with a 6-4, 6-4 defeat of Stefanos Tsitsipas in their opening Green Group clash.
Sindhu will play He Bing Jiao on Friday but that could well be a dead rubber as far as her chances of progressing further are concerned.
The 24-year-old Indian came into the match with a healthy 10-6 head-to-head record against Yamaguchi but she had lost to the Japanese in the last two meetings this year.
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