Five-time former champion Novak Djokovic, the 2018 year-end No. 1 in the ATP Rankings, six-time former titlist Roger Federer, Alexander Zverev, Marin Cilic and first-time participant all practised on Thursday on Centre Court at The O2 ahead of the Nitto ATP Finals.
Singles – Group Guga Kuerten
 Novak Djokovic (SRB)
 Alexander Zverev (GER)
 Marin Cilic (CRO)
 John Isner (USA)
Singles – Group Lleyton Hewitt
 Roger Federer (SUI)
 Kevin Anderson (RSA)
 Dominic Thiem (AUT)
 Kei Nishikori (JPN)
Eight different countries are represented in the elite eight-man singles field for the third consecutive year, with Group Lleyton Hewitt matches beginning on Sunday, 11 November. Group Guga Kuerten matches are scheduled to begin on Monday, 12 November. Gustavo Kuerten won the 2000 season finale, when the event was held in Lisbon, while Lleyton Hewitt won two titles in 2001 (in Sydney) and 2002 (in Shanghai).
Karen Khachanov, who beat Djokovic for his first ATP World Tour Masters 1000 title on Sunday at the Rolex Paris Masters, and Borna Coric are first and second alternates respectively in the singles field.
Doubles – Group Knowles/Nestor
 Oliver Marach (AUT) / Mate Pavic (CRO)
 Lukasz Kubot (POL) / Marcelo Melo (BRA)
 Mike Bryan (USA) / Jack Sock (USA)
 Pierre-Hugues Herbert (FRA) / Nicolas Mahut (FRA)
Doubles – Group Llodra/Santoro
 Juan Sebastian Cabal (COL) / Robert Farah (COL)
 Jamie Murray (GBR) / Bruno Soares (BRA)
 Raven Klaasen (RSA) / Michael Venus (NZL)
 Nikola Mektic (CRO) / Alexander Peya (AUT)
Oliver Marach and Mate Pavic, who have clinched the year-end No. 1 ATP Doubles Team Ranking and have a 4-5 record in tour-level finals in 2018, lead Group Knowles/Nestor, which begins play on 12 November. Colombians Juan Sebastian Cabal and Robert Farah, the second seeds, headline Group Llodra/Santoro that starts on 11 November. Henri Kontinen and John Peers, winners of the Nitto ATP Finals title for the past two years, will serve as first doubles alternates at the season finale. Jean-Julien Rojer and Horia Tecau, winners of the 2015 edition, are second doubles alternates.
Mark Knowles and Daniel Nestor won the 2007 year-end doubles title, while Frenchmen Michael Llodra and Fabrice Santoro picked up the 2005 trophy.