Inter Milan dropped two precious points after being held to a 2-2 draw at Fiorentina and will lose top spot in Series A, should Roma win their home match against Atalanta on Sunday.
A goal eight minutes from time from Per Kroldrup earned the Viola a deserved point after Inter had come from behind to snatch the lead in the second half on Saturday.
Prolific strike duo Diego Milito and Samuel Eto'o had each steered home right-wing centres to cancel out Keirrison's early strike in an absorbing end-to-end contest.
The result means Inter go two points clear of Roma having played a game more, while Fiorentina move up a place to eighth.
With Fiorentina's Peruvian left winger Juan Vargas injured and top scorer Alberto Gilardino only fit enough for the bench, Inter began the match on the front foot with Wesley Sneijder having a 20-yard shot tipped around the post.
From the resulting corner Milito had a glorious chance to put Inter ahead but the Argentine could only hit the post. The Nerazzurri were soon made to pay as Fiorentina sliced through their defence in the 11th minute.
Riccardo Montolivo waited for the right moment to release the marauding Gianluca Comotto, whose squared centre was slammed high into the net from eight yards by Brazilian prospect Keirrison.
Jose Mourinho's men responded by dominating possession but could find no way through the well-organised Viola backline.
The elusive Sneijder fizzed a 25-yarder a foot wide, Maicon sliced a volley horribly off target and Esteban Cambiasso, Cristian Chivu and Eto'o all blasted well over from distance before the break.