Jannik Sinner stunned Novak Djokovic with wins in singles and doubles to send Italy through to a first Davis Cup final for 20 years.Djokovic suffered an unwanted career first when he failed to convert three consecutive match points in a pulsating 6-2 2-6 7-5 singles loss against world number four Sinner.It was Djokovic's first defeat in a Davis Cup singles rubber since a retirement against Juan Martin del Potro 12 years ago, ending a 21-match winning run.Serbia had led 1-0 in the semi-final in Malaga thanks to Miomir Kecmanovic’s win over Lorenzo Musetti but Djokovic’s loss sent the tie to a deciding doubles contest.Djokovic and Sinner lined up on opposite sides of the net for the fourth time in less than two weeks alongside Kecmanovic and Lorenzo Sonego respectively, and it was the Italian duo who clinched a 6-3 6-4 win to send their country through to a clash with Australia for the title on Sunday.After Kecmanovic had backed up his fine showing against Britain’s Jack Draper by coming from a set down to defeat Musetti 6-7 (7-9) 6-2 6-1, the stage seemed set for Djokovic to send Serbia through to the final.The confidence Sinner had gained from his group stage victory over Djokovic at the ATP Finals was negated by a convincing loss in the final but the world number one looked fatigued, perhaps more mentally than physically, during the first set.Both men had headed straight from Turin to Malaga but Sinner is 14 years younger than his rival and he took full advantage of some uncharacteristic errors to reel off five games in a row.Sonego and Sinner get the job done