Home hope Sinner kicks off ATP Finals title bid by breezing past De Minaur
Italian Sinner delighted supporters in Turin with a comfortable win over Finals debutant De Minaur to move first in the Ilie Nastase Group.
The world number one, who hadn't played since winning the Shanghai Masters last month, only had one brief scare when his serve was broken early in the first set.
But he quickly recovered to rattle off four straight games and take the opening set to 5-2 before closing it out with his first set point.
Sinner closed out a routine victory in emphatic fashion with a perfect service game and basked in the applause of his home fans after smashing an ace to finish in style.
"It's a great start for my side for this event, for this tournament, considering I haven't played for four weeks an official match. I'm glad that I managed to play this kind of level today," Sinner told reporters.
"I had in the beginning some moments, which is normal, and then I found myself on the court... I'm very, very happy."
Sinner, who lost last year's final to Novak Djokovic, tops the world rankings after a stunning season in which he claimed the Australian and US Opens - his first Grand Slam victories - and won five more ATP titles.
However, he has been dogged by controversy after twice testing positive for traces of the steroid clostebol in March.
He was initially cleared by the International Tennis Integrity Agency but at the end of September, the World Anti-Doping Agency appealed, seeking a ban of up to two years.
Champion in 2020 and finalist the following year, world number four Medvedev is in the same Ilie Nastase Group as Sinner but earlier boiled with anger during his 6-4, 6-3 loss to American Fritz.
Medvedev destroyed his racket after going a set down and things went from bad to worse when Fritz broke serve to take a 4-2 lead in the second set.
Medvedev was docked a penalty point for throwing his racket at a courtside microphone and during game seven of the second set he held a new racket by its head while waiting for Fritz's serve.
After the match Medvedev, whose behaviour was jeered by the crowd, replied "100 per cent" when asked if he was hoping for the end of the season to come along.
"I'm tired to fight against something that doesn't depend on myself," he told reporters.
"I'll see how it goes. Today actually I had my chances. I'll have them the next matches. If it doesn't work out, I go on holiday. I'm happy."
Carlos Alcaraz will open his bid for a first Finals title in the John Newcombe Group on Monday against Casper Ruud before Alexander Zverev faces Andrey Rublev.
The top two players from each of the tournament's two groups qualify for the semi-finals.
