Nine days after their duel in the final of the Paris Masters, Sinner was again the strongest winning 7-5, 6-1.
But fellow Italian Lorenzo Musetti was earlier outclassed 6-3, 6-4 by American Taylor Fritz.
After a tight first set, Sinner swept aside Auger-Aliassime, who had been hampered by a left calf injury by breaking serve to rush to a 3-0 lead.
He broke him a second time to close out the match with an ace after one hour 41 minutes.
“Obviously winning the first match is very important in this competition and this format,” said 24-year-old Sinner.
“It was a very tough match until 6-5. I had some chances to break. He served very well, only once I missed a return, but it can happen. He played some very aggressive tennis, so I’m happy to overcome a very tough test today.
“I hope it’s nothing too serious,” Sinner added of his rival. “I wish him obviously a very speedy recovery and hopefully he is back to 100 percent physically.”
Sinner notched his 27th consecutive victory on his preferred indoor hard courts surface and took the lead in the Bjorn Borg Group, which will also see the world number two face Germany’s Alexander Zverev and American Ben Shelton.
The native of South Tyrol, the German-speaking region of northeastern Italy, won the 2024 edition of the tournament which brings together the eight best players of the year, by stringing together five wins without dropping a single set.
The 2025 edition could allow him to finish the season as world number one, currently held by his great Spanish rival Carlos Alcaraz, who has beaten him four times this year. (AFP)
