Home favourite Jannik Sinner beat Stefanos Tsitsipas in straight sets on the first day of the season-ending ATP Finals in Turin, Italy.

Greece's Tsitsipas, the 2019 champion, struggled to match his opponent and did not force a single break point.

"I was excited to step on court and opening the Finals is really, really special," Sinner, 22, said.

"I knew it was going to be very tough but I think I handled the situation well. I tried to stay aggressive and I am very happy with the performance.

"I am happy to start off with a win and hopefully I can continue with this intensity."

It is the first time Sinner has qualified for the ATP Finals on merit, having replaced Matteo Berrettini in the line-up for the 2021 edition after his compatriot withdrew through injury.

This year he reached his first Grand Slam semi-final at Wimbledon and won his maiden Masters 1000 title at the Canadian Open in August.

He came into his tie with Tsitsipas having trailed the sixth seed 5-2 in their head-to-head but looked relaxed on court as he saw out the win in one hour 25 minutes.

The ATP Finals features eight of the year's best men's players split into two groups of four, with the top two qualifying for the semi-finals.

Sinner and Tsitsipas are joined in the Green Group by world number one Novak Djokovic and Denmark's Holger Rune, who play later on Sunday (20:00 GMT).

Should he win the match, Serb Djokovic would seal the end-of-year top spot in the world rankings.

Tournament victory, meanwhile, would make him the outright leader for ATP Finals titles, having equalled Roger Federer on six last year.