Novak Djokovic remained on course for a record-equalling sixth ATP Tour Finals title after a 7-6 (7/5), 7-6 (8/6) win over Taylor Fritz in Turin on Saturday.
Djokovic brushed off his bruising encounter with Daniil Medvedev the day before to boss the semi-final against the ninth-seeded American.
The 35-year-old set up a meeting with Norway's Casper Ruud who at 23 years of age will bid for his first major title after sweeping past Russian Andrey Rublev 6-2, 6-4 in the second semi-final in northern Italy.
The Serb has beaten world number four Ruud in all three of their previous meetings including this year in the semi-finals in Rome.
Djokovic will aim for his second major title of the year, after Wimbledon, having missed a significant part of the season, including the Australian Open and the US Open, for his refusal to take the covid vaccine.
"Of course, the last match of the season, I'm going to give it all. I'm going to obviously try my best," said the Serb.
"I'm very happy to be able to compete for another big trophy, one of the biggest ones that we have in our sport."
Victory in Sunday's final will also see him equal Roger Federer's haul of six wins in the tournament comprising the top eight players in the world this season.
"I had to fight to survive," said Djokovic, who has now reached the final of the season-ending event eight times and last won in 2015.
"I didn't feel very reactive or very comfortable. I knew coming into today's match from yesterday's gruelling battle against Medvedev, it would take me some time to adjust and find the dynamic movement I need against Fritz, who is one of the best servers on the Tour."
Fritz was playing his first ATP Final, having replaced injured world number one Carlos Alcaraz.
But the American was punished for his errors and fell to his sixth defeat in as many ties against Djokovic.
The Serb held on largely thanks to the efficiency of his serve and his ability to deliver the fatal blow at the right time, with a stunning forehand winner sealing the first set in a tie-break.
In the second set, Fritz was serving at 5-4 to tie the game one set all, but a wayward backhand into the net handed Djokovic a break point chance which he jumped on sealing victory after another tie-break.
"I think my takeaways are that when Novak has played, he's been the best player," said Fritz.
"There's no doubt about that. When he hasn't played, which is a lot of the year, we've seen a lot of different results because when you take him out of the equation, I think everybody else playing is extremely close in level."
Ruud played in two Grand Slam finals this year at Roland Garros and the US Open, and is participating in the season-ending elite eight-player tournament for the second time, having being eliminated in the semi-finals last year.
Ruud took advantage of a below-par Rublev who had seen off Medvedev and Stefanos Tsitsipas.
The Russian began strongly, winning his first service game to love and only dropped a point on his second.
But as Ruud dug deep to make it 2-2, Rublev imploded conceding eight games in a row to the point of crying into his towel at the change of sides at 3-0 in the second set and sending his coach signs of helplessness.
Behind 6-2, 4-0, he finally managed to hold serve but paid for 23 unforced errors in total against eight for Ruud whose only glitch was dropping serve while serving for the match before sealing victory in 69 minutes.
The Norwegian will bid for his tenth ATP title and fourth this year after Gstaad, Geneva and Buenos Aires, all on clay.
Djokovic, who has won 90 titles during his career, is chasing his fifth tour-level title of the season after Rome, Wimbledon, Tel Aviv and Astana.
The Serb now holds a 45-17 career record at the ATP Finals, which he won in 2008 in Shanghai and in 2012, 2013, 2014 and 2015 in London.
A win on Sunday would be worth $4.7 million.