Inter's bid to claim their 15th Serie A title stalled as second-placed Roma ended the Nerazzurri's season-long unbeaten run with a 3-1 win at the San Siro.
Inter started the day knowing victory would see them land their second successive Scudetto and their hopes were raised when Marco Materazzi's controversial penalty early in the second half cancelled out Simone Perrotta's 44th-minute tap-in.
But Giallorossi captain Francesco Totti fired home a late deflected free-kick and Marco Cassetti added Roma's third in injury time to delay the Inter celebrations.
It is unlikely to be enough to reopen the race for the Scudetto, however. Inter are now 13 points ahead of Roma with six games remaining.