Home favourite and world number one Jannik Sinner became the first Italian to win the ATP Finals title following a dominant 6-4 6-4 victory over American Taylor Fritz on Sunday.

Sinner, who lost last year's final to Novak Djokovic, did not put a foot wrong this time round as he finished undefeated and without dropping a set to earn $4,881,500 in prize money.

In a rematch of this year's U.S. Open final, the 23-year-old Sinner broke Fritz's serve with a fine drop shot to take a 4-3 lead before notching the opener with his 10th ace in the match.

Fritz, the first American to reach the final since James Blake in 2006, also dropped serve in the second set by hitting a forehand long which allowed the Italian to seal the contest in 85 minutes.

"It's amazing. Just an amazing week. For me, it's a first title in Italy, so it means so much to me. I'm very happy about that, it's very special," Sinner, who also beat Fritz in the group stage in Turin, said on court.

"I just try to understand what works best for each opponent, try to play the best tennis possible. That was the key, I played a high-level tournament from my side. At times I couldn't play better, so I'm very happy."

Sinner's stupendous year may have been clouded by an anti-doping controversy but on the court he has proved to be almost unstoppable, winning 26 of his last 27 matches and a tour-leading eight titles.

With his 70th win of the season, Sinner also became the first player to win the ATP Finals without dropping a set since Ivan Lendl in 1986.

Despite the loss, Fritz will reach a career-high fourth in the rankings when the new list is released on Monday.

"I just want to say congrats to Jannik and his team. Insane year, honestly. It's really impressive," the 27-year-old Fritz said.

"Thank you to my team and putting up with me. It's been a great week for me. I felt the love all week long."

Earlier, Kevin Krawietz and Tim Puetz lifted the doubles title after edging Marcelo Arevalo and Mate Pavic 7-6(5) 7-6(6) to become the first German pair to win the tournament.