Inter have retained their Italian Serie A title with three games to spare after second-placed AC Milan were beaten 2-1 at Udinese on Saturday night.
Inter's triumph, in coach Jose Mourinho's first season in charge, is their fourth consecutive Scudetto and their 17th overall.
The champions, who will celebrate their success in Sunday's match with Siena at the San Siro, hold a seven-point lead with Milan only having two games left.
The defeat of their city rivals gave Inter President Massimo Moratti an extra reason to party on his 64th birthday.
Fans are congregating in Milan's central square, at the Piazza del Duomo, to wave flags and celebrate the title while large screens show television pictures of Inter players celebrating in their pre-match base.
Milan needed to avoid defeat in Udine to keep their faint hopes of winning a first title since 2004. But Udinese's Antonio Floro Flores was pulled down in the penalty box on the half-hour mark by captain Paolo Maldini and Gaetano D'Agostino fired home the resulting spot-kick.
Cristian Zapata slammed in at the far post early in the second half to double Udinese's advanatge, while Massimo Ambrosini's stoppage time header proved to be too little, too late for the Rossoneri.
Inter have now joined their city neighbours on 17 Italian league titles with Juventus leading the way on 27.
The first championship in Inter's run of four was given to them in a court room after Juve were stripped of the 2006 title following the Calciopoli scandal.
Their second title was a stroll given Juve were in Serie B and Milan had points deducted from the affair while last term Juve were rebuilding in their first season back in the top flight, meaning Inter again had little competition.
Coach Roberto Mancini was sacked at the end of the campaign for not translating the success on the European stage but Portuguese Mourinho, who has won the Portuguese and English league titles, has continued where the Italian left off.
Their style of play has been criticised by fans and the media but their sheer physical power and the goals of Zlatan Ibrahimovic meant they have lost just three league matches so far this term.
[Inter land Scudetto] - [Week 36] - [Inter reaction] - [Jose Mourinho] - [Massimo Moratti] - [Javier Zanetti] - [Zlatan Ibrahimovic] - [Esteban Cambiasso] - [Davide Santon] - [More Inter players]