Carlos Alcaraz beat Daniil Medvedev to top his ATP Finals group and set up a semi-final meeting with Novak Djokovic.
Wimbledon champion Alcaraz won 6-4 6-4 against the Russian, who had already qualified for the last four of the season-ending event in Turin.
"Obviously Novak is Novak, he's the best player in the world right now," said the Spaniard on facing Djokovic.
Medvedev, an ATP Finals champion in 2020, will face Green Group winner and Italian home favourite Jannik Sinner.
World number one Djokovic, who was beaten by Alcaraz in the Wimbledon final, secured his semi-final spot on Thursday thanks to Sinner's win over Holger Rune.
"It's one of the most difficult challenges that I'm going to face, facing Novak in this tournament that he has won six times," Alcaraz told Amazon Prime Video.
"I'm going to put my best tennis [out there] and I'm going to enjoy it. I'm excited."
Having lost his opening match to Germany's Alexander Zverev, Alcaraz looked back to his best with an assured success over third seed Medvedev.
The 20-year-old broke to love at 3-3 in the first set, then got the crucial break at 4-4 in the second before serving out for a straightforward victory.
Zverev beats Rublev in dead rubber
Later on Friday, Zverev ended his season with an impressive 6-4 6-4 victory over Andrey Rublev.
Despite finishing on the same 2-1 win-lose record as Alcaraz and Medvedev in the round-robin group stage, Zverev came third and missed out on a place in the semi-finals due to his inferior sets-won record.
Meanwhile on Friday, Briton Neal Skupski and his Dutch partner Wesley Koolhof were knocked out of the doubles event when their final match together ended in defeat.
The pair, who have won nine titles in two years together - including Wimbledon in July, lost 6-4 7-6 (7-5) to Rohann Bopanna and Matthew Ebden.
Defending champions Joe Salisbury of Great Britain and the United States' Rajeev Ram beat Australian duo Jason Kubler and Rinky Hijikata 5-7 6-1 10-2 to top the doubles Red Group and progress to the semi-finals alongside Bopanna and Ebden.