Fiorentina denied Inter the chance to head into the mid-season break with a win, Giovanni Simeone converting a stoppage-time equaliser.
Inter failed to arrest their slump in form as Giovanni Simeone's 91st-minute strike earned Fiorentina a 1-1 draw and sent the Nerazzurri into the mid-season break winless in five Serie A matches.
Club captain Mauro Icardi's second-half goal looked set to be enough to get Inter - who have slipped from the summit to third after their 16-game unbeaten start to the campaign ended - back on track, but Simeone dashed those hopes at the death.
Luciano Spalletti's side now face the prospect of staring at a nine-point gap to Napoli, who play Verona on Saturday, during their two weeks off.