Rafael Nadal has withdrawn from the season-ending ATP Finals due to a persistent abdominal injury and will take the time off to have ankle surgery.
The Spaniard lost his place as world number one last week when injury forced him to pull out of the Paris Masters, with Novak Djokovic moving to the top of the rankings.
And Nadal will not get the opportunity to end the year on a high as he will not play in London, citing both last week's abdominal issue and a long-standing ankle problem for his absence.
"It has been a complicated year - very good at the tennis level when I have been able to play and, at the same time, very bad as far as injuries are concerned," Nadal wrote on Twitter.
"I have done everything possible to get to the end of the season in good condition, both to Paris and to London, doing things well, and I really wanted to play.
"Unfortunately, I had the abdominal problem in Paris last week and I also have a free body in the ankle joint that has to be removed in the operating room [on Monday].
"We had detected it for some time and it occasionally bothered me. However, since the problem in the abdominal muscle also prevents me from playing in London, we are taking the time to remove the free body and avoid future problems.
"This way I hope to be in full condition for next season."
Nadal has not featured on the ATP World Tour since retiring in the semi-finals of the US Open in September, also suffering this year with hip and knee problems.
The 32-year-old won the French Open - his 17th grand slam title - but he competed in just three hard-court tournaments in 2018, winning the Rogers Cup while retiring at both the Australian Open and at Flushing Meadows.
Djokovic is set to end the year as number one, having enjoyed a sensational run of results that saw him triumph at Wimbledon and the US Open.
|Murray to miss Open 13 Marseille|
|Solskjaer´s United turnaround no easy task, says Hughton|
|The big Friday Premier League quiz|
|How James Harden´s 2018-19 numbers compare to his MVP campaign|
|It´s insane! - Tsitsipas excited to face ´legend´ Federer|
|Sharapova ends Wozniacki title defence|
|American teen Anisimova sends records tumbling at Aus Open|
|Lakers survive Ball´s gaffe to beat Thunder in OT|
|Federer expects ´athletic´ and ´attacking´ Tsitsipas clash|
|Alcacer is fit and available – Favre|
|Fantastic Federer breezes past Fritz|
|Pogba happy with Man United approach under Solskjaer|
|Mickelson leads Desert Classic, ties career-low with 12-under 60|
|Warriors´ Durant on Curry: He´s a once-in-a-generation, once-in-a-lifetime talent|
|Patriots owner says Brady is greatest player, not just quarterback, of all time|
|Inglis to retire from representative duty this year, NRL in 2020|
|Is Beal better without Wall? Wizards star says it´s ´absolutely nonsense´|
|Rockets C Capela undergoes thumb surgery, expected back after All-Star break|
|This Week in U.S. Sports: Irving apologises, Machado´s agent isn´t happy|
|Knicks in woeful shape, but 2019 could still be bright in New York|
|Valverde not worried about Levante´s Copa appeal|
|Nowell an option for England at flanker, reveals Jones|
|Pellegrini: Arnautovic available for the right price|
|Knicks throw away 19-point lead and lose on last-second goaltending call|
|Tebow invited back to Mets´ major league spring training|
|Canelo and Jacobs agree unification fight|
|Barcelona 3 Levante 0 (4-2 agg): Dembele at the double as Barca advance|
|Levante to lodge complaint over Barcelona Copa selection|
|Kanter´s London absence ´very unfortunate´, says NBA commissioner|
|NBA could swap London for Paris in 2020|
|Spurs coach Popovich uncertain if he will return next season|
|Pistons´ Griffin fined for verbal abuse of official|
|Everton do not have financial conditions to enter transfer market - Silva|
|Andy Cole joins Sol Campbell´s coaching staff at Macclesfield|
|Atletico confirm Saul has thigh injury|
|Wood replaces injured Stone in England squad|
|Lebanon 4 North Korea 1: Disciplinary record cruelly denies Radulovic´s men|
|Saudi Arabia 0 Qatar 2: In-form Ali bags brace as Qatar top group|
|Robertson signs new Liverpool deal|
|Vunipola backs Farrell to thrive in solo leadership role|
|People don´t know what´s going on behind the scenes - Mourinho defends United stint|
|Indefatigable Muguruza knocks out Konta at 3:12am|
|Serena coasts, difficulties for Halep and Muguruza´s marathon|
|Lowry retains Abu Dhabi lead|
|Djokovic battles past Tsonga, young guns flourish|
|Louisville airport to be renamed in Muhammad Ali´s honour|
|Emery not thinking about Ozil speculation|
|Sri Lanka hopeful over Kusal Mendis finger injury|
|Oman 3 Turkmenistan 1: Last-gasp Al-Musallami guarantees progression|
|Emery wants Cech to end career ´in a good moment´|
|Japan 2 Uzbekistan 1: Shiotani stunner seals comeback and top spot|
|Calhanoglu deal ´financially impossible´ for Leipzig|
|Not seen at Aus Open since Nadal, Djokovic and Murray in 2009 – ´Next Gen´ make move|
|Martial: Solskjaer lets me express myself|
|Djokovic sees off Tsonga to reach third round|
|Returning Cousins calls Warriors ´the most hated team in sports´|
|Halep injury ´nothing dangerous´|
|Warner picks up elbow injury in Bangladesh|
|Mkhitaryan returning to Arsenal training next week|
|Leeds United pounce for Real Madrid goalkeeper Casilla|
|Watson lights up Gabba before power cut forces abandonment|
|Superb Serena blows Bouchard away|
|Tevez, Hulk, Oscar, Lavezzi - how the CSL stars Dembele is following to China fared|
|Thiem retires from Australian Open|
|Osaka ´not telling´ when it comes to injury niggle|
|Fabinho enjoying Klopp´s management style|
|Halep battles past Kenin in Melbourne|
|Hartley to miss England´s Six Nations opener|
|Dembele departs Spurs for Guangzhou R&F|
|Nacho convinced Isco remains important to Real Madrid|