Roger Federer begins the tournament with hope he can win his 100th career title. "This event is the biggest event that the ATP owns and you have the best eight players in the world in a unique format, a round-robin system".
"Every tournament I will play for the rest of my life I will have a chance to reach my 100th, but reaching it here in London would be extra special, having achieved so much success here and because of the importance of the tournament", commented Federer, who will play his first game against Japan's Kai Nishikori in Sunday evening. That's because the man he overtook, Rafael Nadal, is done for 2018.
Back inside the Top 10 for the first time since August 2017, Nishikori's road to the being considered one of the best players in the world started off by losing a first round challenger match at the beginning of the year.
Perhaps the match most indicative of this was his straight-set demolition of Federer on the high-speed courts at the Cincinnati Masters in mid-August. But at the same time I feel as a general idea of this event is that it travels more'. Federer will lead the charge in Group Lleyton Hewitt, which also consists of Dominic Thiem, Kevin Anderson and Kei Nishikori. I expect the match between Zverev and Cilic to be the eventual quarterfinal. The Japanese has also had the better of Thiem the last time the two guys met, in the Vienna quarterfinal.
Djokovic, who underwent elbow surgery in February and ended the year as world No. 1, received the Comeback Player of the Year award on Friday. A quarter-final run in Rome and Wimbledon saw him back in the Top 20.
Djokovic is set to end the season at the top spot after Nadal chose to withdraw from the London event.
Anderson is the other debutant and will become the first South African in 23 years to grace the season-ender.
Zverev, 21, has been touted about as one of the leaders of the new generation and has won three Masters titles in his short career but he has flattered to deceive at the Grand Slams.
Its longest stay in a single venue was across 13 consecutive editions at Madison Square Garden from 1977 to 1989 but it has been held at London's O2 arena since 2009 - drawing more than 250,000 fans annually.
Novak Djokovic can now add the "Comeback Player of the Year" award to his vast collection of honours and the Serb can complete his remarkable resurgence by winning a record-equalling sixth title at the ATP Finals next week.