Roger Federer insists Rafael Nadal will be missed after the Spanish star pulled out of the season-ending ATP Finals.
Nadal won his 11th French Open title at the start of the year but has since endured a frustrating season, struggling with a host of injuries.
The 32-year-old was forced to retire from his US Open semi-final against Juan Martin del Potro and the problems have continued to plague his season since.
Nadal was hopeful of participating in the ATP Finals in London but confirmed last week he required surgery on his ankle and would miss the tournament.
And Federer said: In terms of excitement and star power and legendary status… hes going to be missed.
But we move on, wish him the best and hope he can recover well and come back strong against next.
Now the focus is on the players here and hopefully the fans can enjoy some great tennis.
Nadals withdrawal meant Federer and Djokovic were drawn in opposite groups, with both expected to progress and potentially meet each other in the final at the O2 arena.
Speaking after his ankle surgery, Nadal confirmed the operation had gone well.
He said: Hello everyone, thank you for the messages I received. The ankle surgery went well.