Roger Federer goes into the ATP Finals ranked third in the world, with Rafael Nadal sitting narrowly above Novak Djokovic at the top.
The Swiss veteran will be hoping that the Spaniard’s injury issues don’t help his Serbian rival achieve victory, as he looks to keep hold of his record amount of titles at the season-ending showpiece.
The 38-year-old is the only man to have won the tournament six times during his career, but that could be matched this time out.
Djokovic, who is six years his junior, has time on his side in his quest to become the most successful player in ATP Finals history, and he has already won it five times.
Federer lifted the trophy for the first time way back in 2003, and followed up with wins in 2004, 2006, 2007, 2010 and 2011.
Djokovic made his name at the tournament back in 2008, and won it again in 2012, 2013, 2014 and 2015.
The 2019 Wimbledon champions sits alongside Ivan Lendl and Pete Sampras in having won it five times, and Federer will be looking over his shoulder.
Djokovic will also have an eye on Nadal, who has never won the tournament, but is a doubt to even compete after struggling through injury.
Matteo Berrettini will be making his first appearance at the finals on Sunday after a breakthrough year on the ATP tour, and he has since given his opinion on coming up against two of the ’Big Three’ so far this year.
He said: “Federer uses so many variations, that as you play with it, you want to stop and watch it to understand, and understand its secrets.
“He always plays a different game and they are all difficult to guess. The conclusion is obvious, it does not allow you to understand how to hurt him.
“Nadal, on the other hand, makes you feel a lot about his presence in the field, his imperious gestures, his looks, his competitive spirit.
“It is not anxiety, but tension for an important match. And he takes you to a thousand.”
He added: “I know that I am not a favourite, but I am very motivated to do well and give it all.
“For months I could not even dream of qualifying so I did not give up anything now.”