Sinner foils Djokovic to pull Italy level with Serbia in Davis Cup semi
The winners will face Australia in the final on Sunday, with Djokovic and Sinner to return for the final doubles rubber.
"It was an incredible match, we were one point away from being out of this competition and we are still here," said Sinner after the 6-2, 2-6, 7-5 win over 24-time Grand Slam winner Djokovic.
After Miomir Kecmanovic stormed back from a set down to dispatch Lorenzo Musetti 6-7 (7/9), 6-2, 6-1, Djokovic was aiming to complete the job and send Serbia into the final for the first time in a decade.
However Sinner beat the 36-year-old for the second time in 11 days, snapping Djokovic's run of 22 consecutive singles wins in the Davis Cup.
The world number four won the first of the trilogy in the ATP Finals group stage, but although Djokovic took the second to earn the title, Sinner delivered again in front of a full house at the Martin Carpena arena.
After an impenetrable performance in the victory over Cameron Norrie on Thursday, Djokovic created headlines by rowing with noisy British fans and then showing his fury at being asked to take a doping control test before that match.
Sinner, 22, earned the first break for a 2-1 lead after Djokovic doubled faulted and then sent a backhand volley into the net.
The Serbian started way below par and Sinner converted the second of two break points with a backhand down-the-line winner and then consolidated to fly into a 5-1 lead.
The Italian finished his superb first set with an ace, hitting 12 winners to the subdued Djokovic's one, in only 38 minutes.
With the match seemingly under control he let it slip, double faulting on the first break point he conceded to fall 3-1 behind.
Sinner allowed Djokovic back in and he ruthlessly capitalised, sealing the set with another break when Sinner whipped a forehand wide.
Finding the level
With his eye in, Djokovic made just three unforced errors in the second set to Sinner's 10.
The Serbian, who has won seven titles this season including three Grand Slams, had the momentum.
Djokovic was on top in the third set with Sinner saving two break points and unable to pressure the Serb's serve.
Sinner appeared to crack in the 10th game, sending two balls wide and then hitting the net to give up three match points, but then won five consecutive points to hold for 5-5. He then broke Djokovic and held comfortably to triumph.
Italy, who won the Davis Cup for the only time in 1976, started well in the first singles rubber too.
Musetti, chosen to play by Italy coach Filippo Volandri over Matteo Arnaldi, who played in the first singles in the last eight win over the Netherlands, edged a nail-biting first stanza.
The world number 27 conceded a service break in the first game, but battled his way back in for 5-5, the first break Kecmanovic has conceded in an impressive week.
In the tense tie-break Musetti converted his third set point to take the lead, but Kecmanovic responded strongly in the second set.
The Serbian broke at the third time of asking for a 4-2 lead, when Musetti hit the net with a backhand volley and then clinched the set with another break.
In full flow, Kecmanovic broke twice in the third to rack up a 5-0 lead, winning nine consecutive games, with Musetti getting treatment on his left hamstring as the match slipped away.
Kecmanovic swept to victory with a powerful forehand winner, falling to the floor in delight.
"It wasn't easy at all, I wasn't positive after the first set," said the world number 55, chosen over the higher-ranked Laslo Djere.
"But I knew that if I wanted to have a chance to win, I had to switch the mindset and, especially now when you play for so much, you know you're going to give everything you have."
