While Djokovic qualified for the knockout stages as runner-up in the Green group, his Wimbledon final foe topped the Red group standings by defeating Daniil Medvedev on Friday.
The year-end world number one ranking may have been ripped out of Alcaraz's grasp by Djokovic, but the world number two could enjoy a small dose of vengeance by ending the Serbian's ATP Finals title defence, thereby denying him a record seventh year-end championships crown in the process.
On his belated debut at the ATP Finals - having forgone his chances of glory last year due to injury - Alcaraz responded to his opening defeat to Alexander Zverev by powering his way past an overly emotional Andrey Rublev, leaving his fate in his own hands ahead of Friday's afternoon battle with Medvedev.
A couple of months on from surrendering his US Open crown with a semi-final loss to the hard-court specialist, Alcaraz strode to a 6-4 6-4 beating of Medvedev with one hour and 20 minutes on the clock, in turn usurping the Russian to the top of the Red group standings.
After saving two break points in his second service game, Alcaraz did not come under the cosh against Medvedev again and capitalised on a few too many mistakes from the 2020 champion, striking 22 winners and proving too hot to handle with his quintessential aggressive approach en route to the final four.
At 20 years and 196 days old, Alcaraz is the third-youngest player to compete in the semi-finals of the year-end championships - only Andrei Medvedev (1993) and Rafael Nadal (2006) were younger - and the latter was involved the last time the top-two ranked players in the world met in an ATP Finals semi-final in 2007, losing to Roger Federer.
While Djokovic was able to quell the youthful energy of Danish protege Holger Rune in his opening Turin battle, the Serbian's defeat to Jannik Sinner on matchday two left the champion's fate out of his own hands before taking to the court with alternate Hubert Hurkacz on Thursday afternoon.
As is customary in matches with the towering Pole, Djokovic had to fend off a barrage of aces from Hurkacz - 24 to be exact, quadruple the amount Djokovic managed - and the Serbian would be taken all the way by the world number nine, who sent Sinner through to the last four by taking the second set.
However, as Djokovic typically remained calm and composed in the final set - winning 86% of points on his second serves - Hurkacz was left to rue a succession of unforced errors, as the holder raced to a 7-6 4-6 6-1 victory to give himself a fighting chance of semi-finals qualification.
The Djokovic camp were rooting for Sinner to overcome Rune, who would have eliminated the Serbian by beating the home favourite, but with Sinner also getting the job done in three sets, Djokovic advanced to the final four behind the Italian trailblazer with a 2-1 record in the Green group.
A 12th ATP Finals semi-final appearance sees Djokovic draw level with Ivan Lendl for second on the all-time list behind Federer's 16, and should the 36-year-old reach the championship match for the ninth time, either Sinner or Medvedev will provide the final obstacle to year-end title number seven.
Tournament so far
Round robin: vs. Alexander Zverev 7-6 3–6 4–6
Round robin: vs. Andrey Rublev 7–5 6–2
Round robin: vs. Daniil Medvedev 6-4 6-4
Round robin: vs. Holger Rune 7-6 6-7 6-3
Round robin: vs. Jannik Sinner 5-7 7-6 6-7
Round robin: vs. Hubert Hurkacz 7-6 4-6 6-1
Head To Head
Madrid Open (2022) - Semi-final: Alcaraz wins 6-7 7-5 7-6
French Open (2023) - Semi-final: Djokovic wins 6-3 5-7 6-1 6-1
Wimbledon (2023) - Final: Alcaraz wins 1-6 7-6 6-1 3-6 6-4
Cincinnati Masters (2023) - Final: Djokovic wins 5-7 7-6 7-6
Talk about a knife-edge - both Alcaraz and Djokovic have two wins under their belt against the other since their first ATP Tour contest in 2022, as the quartet of blockbuster battles began with the Spaniard edging a Madrid Open semi-final on home turf last year.
A French Open semi-final showdown this season initially lived up to the hype as well, only for Alcaraz's body to betray him after the second set as Djokovic progressed, but there would be no similar physical collapse from the 20-year-old en route to a famous Wimbledon triumph over the Serbian this summer.
Not only did Alcaraz's spectacular five-set win deny Djokovic a calendar-year Grand Slam, he also broke the 36-year-old's 45-match winning run on Centre Court at SW19, as well as his 34-match overall victorious streak at Wimbledon.
The Spaniard was on the path to successive wins over Djokovic in August's Cincinnati Masters final - their only hard-court meeting to date - but the latter's monster mentality in tie-breakers won out as he edged yet another gruelling battle.
We say: Djokovic to win in three sets
For the more superstitious supporters, Alcaraz and Djokovic have followed a win-loss sequence since first butting heads, meaning that the former is due for another victory over the reigning ATP Finals champion if that pattern is to be followed in Turin.
With both world-beaters possessing unrivalled defensive and offensive qualities, the victor of Saturday's headline battle may very well come down to who refuses to crumble under pressure, who makes fewer unforced errors and who boasts the fresher pair of legs - factors which only just tip our scales in Djokovic's favour.
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