The septuagenarian has emerged as the No.1-ranked Indian player on the ITF seniors tour.
A sell-out crowd in Turin's Pala Alpitour had hoped to cheer the 22-year-old Sinner to the biggest title of his career but Djokovic was simply in a different league.
The 20-year-old Alcaraz, who also has won six titles this season, missed out on becoming the youngest finalist in the season-ending tournament since Pete Sampras in 1991.
Alcaraz will face Green Group runner-up Novak Djokovic in a mouth-watering semifinal.
Home favourite Sinner also clinched top spot in the group with a 3-0 record.
The earlier Green Group clash was a non-event as Stefanos Tsitsipas retired injured against Holger Rune.
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.
'Djokovic is also more successful because he has had a level of fitness/physique that has allowed him to play more than me,' added Nadal.
Djokovic said he received advice on his own career from Bryant, who died in 2020 in a helicopter crash that also killed his daughter, Gianna, and seven others.
The Serbian is the first man to win three Grand Slam events in the same season four times.