Ivan Cordoba thrashed in a stoppage-time goal to give Inter a 3-2 win at basement club Reggina and send the champions top of Serie A after they had surrendered a two-goal lead.
Inter looked to be cruising early on when goals by Brazilian defender Maicon and France midfielder Patrick Vieira had them 2-0 up within 23 minutes.
But Francesco Cozza resuscitated Reggina's hopes in the 34th with a powerful strike from the edge of the area and Franco Brienza equalised with another long-range effort eight minutes after the break.
Inter have 21 points from 10 games, one more than Napoli and Udinese.
Strugglers AS Roma visit Juventus later today.