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The 23-year-old Italian, roared on by frenzied home support inside SuperTennis Arena, clawed his way to a 6-3 6-7 (5-7) 7-6 (17-15) victory with the third-set tiebreak one of the best in the competition's rich history.

Both players produced some spellbinding tennis in a series of punishing rallies in the breaker with the big-serving Bergs looking as though he would extend the tie to the doubles.

But Cobolli, who also failed to convert his first six match points, would not be denied and eventually fired down an unreturnable serve to spark wild celebrations in the stands.

Earlier, Matteo Berrettini powered past Raphael Collignon 6-3 6-4 to put Italy in front. It was Berrettini's eighth successive match win in the competition after he won all six he played last year as Italy retained the title.

Italy will try to complete the three-peat in Monday's (AEDT) final against either Germany or Spain, which face off on Sunday (AEDT).

Should it prevail, it would become the first nation to win three successive titles since the Challenge Round was abolished after the 1971 event.