Italy's Jannik Sinner got his title defence off to a solid start with a dominant straight-sets win over ailing Canadian Felix Auger-Aliassime at the ATP Finals on Monday in Turin.
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 per cent 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.
'FIRED UP' FRITZ
Earlier, Fritz got his bid for a first ATP Finals crown off to the best possible start with a comprehensive win over Musetti.
The 28-year-old American, who lost to Sinner in last year's final, was out of the blocks quickly in the Jimmy Connors group match, taking an early break and holding on to pocket the first set.
The crowd did their best to lift a visibly fatigued Musetti, who was a late addition to the line-up.
He only qualified for the Finals on Saturday after Novak Djokovic pulled out with injury, shortly after beating the Italian in the final of the Athens event.
Winning 84 per cent of his first serves and giving away just four break-point chances, none of which were taken, Fritz continued to control the match.
The American broke to go 3-1 up and served cleanly all the way to the line.
"I am really happy. I thought I did a lot of things really well," Fritz said.
"I did a great job early on in the match to serve my way out of trouble and save some break points. The whole second set I played well and had a lot of chances to break that I didn’t get.
"I am really happy I was able to serve it out there and it didn’t come back to ruin it."
Fritz qualified sixth for the Finals and after finishing runner-up last year is gearing up for another tilt at the title.
"Every time I come here, I like the conditions and it is very easy to get motivated and fired up," said Fritz.
"You can lock in, it is the last tournament of the year and it is the ATP Finals, it's a big deal.”
Neither player will have time to rest as both are back on court on Tuesday.
Fritz faces Carlos Alcaraz, who also got off to a winning start by beating Alex de Minaur on Sunday while Musetti takes on the Australian.