Novak Djokovic must get past Casper Ruud for his first ATP Finals crown since 2015 after defeating Taylor Fritz in straight sets in Turin.
The Serb was made to work by the 25-year-old Californian, with both sets going to a tie break.
But Djokovic, 35, edged it both times, winning 7-6 (7-5) 7-6 (8-6) and now faces Norway’s Ruud – who defeated Andrey Rublev – in Sunday’s final.
“I had to fight to survive,” said Djokovic.
“I knew coming into today’s match from yesterday’s gruelling battle against [Daniil] Medvedev I knew 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.
“I am very pleased to have overcome this one as I don’t think it was one of my best days with my tennis, but I managed to hang in there.”
Despite not winning the end-of-season showpiece for seven years, five-time champion Djokovic is now only one match away from equalling Roger Federer’s record of six titles.
Ruud stands in his way after the 23-year-old swept past Russia’s Rublev 6-2 6-4 in Saturday’s second semi-final.
Britain’s Salisbury reaches doubles final
Joe Salisbury will also be part of Sunday’s finals day line-up after the Briton and his American partner Rajeev Ram beat top seeds Wesley Koolhof and Neal Skupski 7-6 (9-7) 6-4 in the first doubles semi-final.
It means Salisbury and Ram remain undefeated in Turin after also winning all three matches in the round robin stage.
However, fellow Briton Skupski and his Dutch partner Koolhof – who also lost to Salisbury and Ram in the US Open final this year – will remain the number one doubles pairing in the world this year after wining seven tour-level trophies in 2022.
Another Briton, Lloyd Glasspool, missed the chance to go up against his compatriot in Sunday’s doubles final as he and Finnish partner Harri Heliovaara were beaten in the second semi-final.
They lost 6-4 6-7 (4-7) 10-6 to Croatian pairing Nikola Mektic and Mate Pavic, who will now face Salisbury and Ram.