All four secured their passage to the semi-finals throughout the week, with Murray and Djokovic winning all their matches.
Djokovic and Murray, both 29, are in with a shot of finishing the year as the world’s top-ranked player and could potentially meet in the final to decide who ends as No. 1.
Raonic and Nishikori will certainly have something to say about that, so here’s a full preview of what’s ahead for all involved:
Murray v Raonic (2pm)
Murray is aiming for personal record of 23 straight wins after equalling his previous best effort of 22 with a win against Stan Wawrinka.
The Scot beat Wawrinka, Nishikori and Marin Cilic to get this far and knows he must match or better Djokovic’s result at this event to remain in that all important top ranking spot.
With Djokovic playing in the evening, Murray won’t want to take any chances and push home a win.
Murray v Raonic
Head to head: Murray 8-3 Raonic
Meetings in 2016: Murray: 5-0 Raonic
Last meeting: Paris Masters SF 2016 – Murray won by w/o
Last Raonic win: Indian Wells R16 2014 – 4-6 7-5 6-3
Previous ATPWTF Matches: None
Standing in his way is big-serving Canadian Raonic, who has defied the odds to get this far.
The 25-year-old, who’s thumped down 40 aces so far, looked set to miss the event after picking up a thigh injury that saw him pull out of a semi-final (against Murray) in the Paris Masters.
His withdrawal confirmed Murray’s ascent to the top of the rankings and he was expected to miss the World Tour Finals.
But three matches into the tournament, Raonic looks fresh and insists his thigh is causing him no issues.
He narrowly lost to Djokovic, with the Serb winning two narrow tiebreaks, while beating both Gael Monfils and Dominic Thiem in straight sets.
Prediction: Murray in 2.
The Scot has picked his battles well so far and should do so again against the Canadian.
Expect close sets and don’t be surprised if the result is very similar to Raonic v Djokovic.
Djokovic v Nishikori (8pm)
But the Serb has shown signs of being back to his very best and has come through his opening matches in largely comfortable fashion.
Heading into this match, Djokovic has won 21 of his last 22 matches at the season-ending showpiece event, racking up four consecutive titles on his way.
The pair have met at the last two World Tour Finals, with Djokovic winning both.
Djokovic v Nishikori
Head to head: Djokovic 10-2 Nishikori
Meetings in 2016: Djokovic: 6-0 Nishikori
Last meeting: Canada Masters – Djokovic won 6-3 7-5
Last Nishikori win: US Open SF – 6-4 1-6 7-6 (7-4) 6-3
Previous ATPWTF Matches: Djokovic 2-0 Nishikori
Nishikori, who is fighting it out with Raonic to end the year as world No. 3, has been in excellent form in London and was perhaps unlucky not to beat Murray in the second match in Group John McEnroe.
The Japanese star cruised past Wawrinka in his opening clash and had already secured passage to the semi-finals before his final match against Cilic.
He wasn’t overly inspiring in his clash with the Croat and lost 3-6 6-2 6-3.
Prediction: Djokovic in 3
Nishikori has impressed so far and will take heart from his performance against Murray, but Djokovic looks supremely focused.
It should be close and Nishikori could easily pinch a set but Djokovic is ruthless on this surface and should reach the final.