The ATP World Tour Finals are the annual season-closing event in the men's tennis world, pitting the year's best eight singles players and doubles duos up against each other in one big showdown.

For the first time this year the tournament is taking place in Turin, in Italy, after several years based in London. Here's everything you need to know about when it's taking place, who's playing, and how to watch live.

When are the ATP Finals?

The World Tour Finals are taking place in Turin from 14-21 November 2021. There are two singles matches and two doubles matches each day except the final Sunday, with the first six days devoted to the group stages (more on that below), the semi-finals on Saturday 20th, and the finals on Sunday 21st.

Who's playing?

The biggest player in the mix this year is undoubtedly Novak Djokovic, hoping to tie Roger Federer's record of six wins at the year-ending tournament.

He's joined by the likes of Medvedev, Zverev, Tsitsipas, and other top players from the men's game - though neither Nadal nor Federer made the cut this year.

There's also already been one early upset. Home favourite Matteo Berrettini had to withdraw from his opening match with an injury, and may be replaced by the first alternate - and fellow Italian - Jannik Sinner.

Here's the full singles draw:

Green Group

Red Group

Novak Djokovic Alexander Zverev
Stefanos Tsitsipas Daniil Medvedev
Andrey Rublev Hubert Hurkacz
Casper Ruud Matteo Berrettini

And here are the doubles players:

Green Group

Red Group

N Mektic / M Pavic R Ram / J Salisbury
M Granollers / H Zeballos J Murray / B Soares
I Dodig / F Polasek P Herbert / N Mahut
K Krawietz / H Tecau J Cabal / R Farah

How to watch on TV or online

If you're in the UK then the easiest way to watch the tennis this year is through Amazon Prime. The streaming giant has rights for almost the whole ATP Tour, including the Finals, so you'll be able to stream the tennis on your PC, phone, smart TV, games console, or more.

Of course you do have to pay for Prime, with Prime Video from £7.99/$8.99 per month, but if you've not tried it before you can get a 30-day free trial which will cover the full tournament and then some.

If you're in the US the tournament will be broadcast on The Tennis Channel, which may be available on your cable plan, or through the Sling sports add-on.

Finally, wherever you are in the world you can also watch every match on Tennis TV, the ATP's official streaming platform. You can choose to pay either monthly or annually, and it includes almost every ATP tournament (but not the WTA, Davis Cup, or any of the Grand Slams).

What's the tournament format?

The ATP World Tour Finals are a bit different to most of the other tournaments through the year. Rather than a knock-out format, the contest uses the round robin structure. 

That means that across the first six days, each player (or doubles pair) will play every other player in their group, for a total of three matches each. The top two players/teams from each group will advance to Saturday's semi-finals, and the winners of those matches play in Sunday's final.

Players get 200 ATP ranking points per round robin win, 400 for a semi-final win, and 500 for a final win - for a potential total of 1500 points for an undefeated champion. Meanwhile prize money goes up to a potential $2,316,000 for an undefeated singles champion, and $429,000 for doubles. The total money and points earned depend on how many matches they win along the way.

All the singles matches are the best of three sets, with tie-breaks, including the final. All doubles matches are two sets with a match tie-break.