Carlos Alcaraz became the fourth and final player to confirm a spot in the semi-finals of the ATP World Tour Finals by overcoming Daniil Medvedev in his final Red group battle.

The world number two had fallen to Alexander Zverev in his inaugural year-end championships contest before getting the job done against Andrey Rublev earlier this week.

However, a spot in the final four was still Alcaraz's to lose, and the Spaniard ensured that he would be present in the knockout stages courtesy of a 6-4 6-4 beating of Medvedev, who had already confirmed a top-two finish in the Red group.

Alcaraz saved both break points he faced and won 67% of points behind his second serve, as well as hitting 22 winners compared to Medvedev's 14 to pip the Russian to top spot in the standings.

The 20-year-old's reward will be a blockbuster meeting with reigning champion Novak Djokovic in the semi-finals, where the two Wimbledon finalists will vie to meet Jannik Sinner or Medvedev in the showpiece match.

"It's one of the most difficult challenges that I'm going to face, facing Novak in the Nitto ATP Finals, where he has won six times," Alcaraz said on the court ahead of his showdown with Djokovic.

"Novak is Novak. He is the best player in the world right now. He's lost just six matches this year, he's unbelievable. I'm going to play my best tennis and enjoy it the same way I did the past few matches. I'm excited to face Novak."

The round-robin stage of the ATP Finals will close on Friday evening with an inconsequential showdown between Rublev and Zverev, both of whom are only playing for pride after being eliminated from semi-final contention.