Roger Federer was favourite to win the ATP Finals in London, but the Swiss ace was beaten in the semi-finals by David Goffin.
Federer pinpointed the loss to Tommy Haas in Stuttgart and to Evgeny Donskoy in Dubai which cost him the spot.
With the expected return from injury of Novak Djokovic, Andy Murray, Stan Wawrinka, Kei Nishikori and more, Roger Federer is expecting an "epic" start to the new year.
Federer had a disappointing end to the 2017 campaign, losing the ATP World Tour semi-finals to David Goffin.
Federer explained that he would earlier be ecstatic at the prospect of sharing the court with the legends of the game.
Rafael Nadal saw off the challenge from Federer and claimed the year-end number one ranking for the fourth time in his career.
The Swiss veteran won seven titles this year, including the Australian Open and a record eighth Wimbledon title, to overtake Pete Sampras' seven championship wins.
British tennis has adopted an extra week in the calendar - but interest in the ATP World Tour Finals is diminishing.
The Swiss ace skipped the entire clay court swing of the season this year following a blistering start to the season.
Although they are not his goals at the moment, Roger Federer has refused to rule out the possibility of competing in the Davis Cup and the 2020 Tokyo Olympics.
Federer made it three wins from three in the round robin stage of the season-ending tournament, with a victory over Marin Cilic in straight sets.
Roger Federer lost his chance of claiming the world No.1 ranking when he withdrew from the Paris Masters.
Murray last featured at Wimbledon where he suffered a quarter-final loss to Sam Querrey and has taken the rest of the year off to recover from a hip injury.
Rafael Nadal pulled out of the ongoing ATP World Tour Finals in London owing to a knee injury that has troubled him since the Shanghai Masters in October.
Roger Federer has revealed that getting surgery on his knee in 2016 made him think his career was ending once and for all.
Roger Federer was a contender for the year-end world number one spot but was beaten to it by long-time rival Rafael Nadal.
Former world number one Mats Wilander believes despite the lack of success for the next generation, the experience of playing Rafael Nadal and Roger Federer will prove crucial.
Roger Federer has continued what has been a remarkable year after becoming the top prize money in all of individual sports.
Federer backed Zverev, Shapovalov and Kyrgios to emulate members of the current big four after his win over Zverev at the ATP Finals in London.
World number one Rafael Nadal is in danger of missing out on the 2018 Australian Open after pulling out of the ATP Finals due to a recurring knee injury.
Rafael Nadal's decision to play the ATP Finals in London has been questioned after he was forced to withdraw after just one match.
Former British number one Annabel Croft believes Roger Federer will only retire when he stops enjoying the sport of tennis.