The duo will play a charity match in front of 48,000 people in Cape Town
Nadal will finish the year as the World Number One after Djokovic lost to Federer
Nadal leads Djokovic with 640 points in their race to finish as the year-end World Number One
Zverev defeated Nadal 6-2, 6-4 in the Nitto ATP Finals in London
Nadal has never won the ATP Finals title while Djokovic won it five times
Federer needs to reach the semis in Holland to become the oldest world No 1 in tennis history, beating Andre Agassi to the crown.
Dimitrov had a brilliant 2017 campaign, winning the Nitto ATP Finals, which propelled him to a career high third in the rankings.
Roger Federer has arrived in Australia to participate in the Hopman Cup and resume his preparation ahead of his Australian Open defence which begins next month.
Nadal will be making his 14th appearance in ATP Barcelona, having won it a record 10 times.
Former world number 9 and fellow Swiss Marc Rosset believes Roger Federer was mentally tired by the end of the ATP Finals in London.
The duo have won everything there is to win – 16 Grand Slams, 30 Masters Series titles and two Olympic gold medals.
Federer had a disappointing end to the 2017 campaign after losing the ATP World Tour semi-finals to David Goffin.
Former British number one Greg Rusedski believes Roger Federer will be rueing his missed chance of winning the ATP Finals after the absence of Rafael Nadal and Novak Djokovic.
Federer pinpointed the loss to Tommy Haas in Stuttgart and to Evgeny Donskoy in Dubai which cost him the spot.
World number three Grigor Dimitrov is expecting an interesting 2018 with the returns of Djokovic and Murray while he is also aiming for a Grand Slam following his ATP Finals win.
Current world number four Dominic Thiem believes the return of Novak Djokovic and Andy Murray will cause a shift in the ATP rankings.
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.
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.