MALAGA, Spain (AFP) — A "proud" Jannik Sinner beat world No. 1 Novak Djokovic twice in one day to send Italy into the Davis Cup final with a 2-1 win over Serbia on Saturday in Malaga.

Italy, who won the trophy for the first and only time in 1976, will face 28-time winners Australia on Sunday.

Sinner, which has now triumphed three times in four clashes across 11 days against the usually unstoppable Djokovic, crucially kept Italy in the tie by beating the 24-time Grand Slam winner 6-2, 2-6, 7-5 in the second singles rubber.

Sinner and Lorenzo Sonego then defeated Djokovic and Miomir Kecmanovic 6-3, 6-4 in the decisive doubles to clinch victory, after Kecmanovic had dispatched Lorenzo Musetti 6-7 (7/9), 6-2, 6-1 in the opener.

World No. 4 Sinner saved three match points as he faced Djokovic in the singles, with the 36-year-old arriving in stellar form.

"I have to be really proud about how I handled the situation," Sinner said.

"Tomorrow we have a great opportunity, we know this but we try to stay as relaxed as possible, keeping the smile in our head."

Djokovic, who has won seven titles this year including three Grand Slams, was aiming to send 2010 champions Serbia into the final for the first time in a decade.

Sinner, however, claimed arguably the biggest win of his career, becoming the first man to beat Djokovic in a singles match at the Davis Cup since Argentina's Juan Martin del Potro in 2011, ending a 21-match streak.

"Congratulations to Italy for qualifying for (the) finals," Djokovic said.

"They deserved it, they played really well, particularly Jannik, in singles against me and then doubles, as well."

"He barely missed the ball the entire match — so you can only say congrats and hats down for the performance like that."

Sinner won the first of their four recent battles in the ATP Finals group stage, but although Djokovic took the second to bag the title, Sinner delivered twice more in front of a full house at the Martin Carpena arena.