Rafael Nadal has confirmed the ankle operation that forced him to withdraw from the ATP World Tour Finals went well.
The Spaniard has endured a frustrating season since winning his 11th French Open title in June.
Any hopes of a strong finish to the season were also ended as Nadal, 32, continued to experience setbacks.
Pulling out of the Paris Masters last week handed Djokovic the world number one seeding, and Nadal will not be able to reclaim top spot after also missing the ATP Finals in London.
But his ankle operation at least appears to have gone well, with Nadal providing an update to his fans on Twitter on Tuesday.
Hello everyone, thank you for the messages I received, he posted.
The ankle surgery went well and from home I am informing you that we postpone the exhibition party planned for the victims in Llevant de Mallorca.
Hola a todos. Gracias por los mensajes que he recibido ayer y hoy. La operación en el tobillo fue bien y ya desde casa comentaros que aplazamos el partido de exhibición previsto en beneficio de los damnificados en Llevant de Mallorca.
— Rafa Nadal (@RafaelNadal) November 6, 2018
Djokovic is the favourite to win the ATP Finals but will face competition from long-term rival Roger Federer, who he narrowly defeated in the Paris Masters semi-finals.
Boris Becker believes Federer may topple world number one Djokovic in London after the draw appeared to work out in the Swiss legends favour.
I would reckon the Novak Djokovic group is the tougher one, said the German, who coached Djokovic for three years.
Normally the big servers prefer indoors because they have the advantage. Roger Federer has a big serve too so it will be interesting.