Samir Handanovic gifted Napoli the lead, fumbling Lorenzo Insigne’s cross into his own net in the first half.
Romelu Lukaku twice hit the woodwork for Inter before Christian Eriksen speared home a left-footed equaliser.
Napoli stay fifth, two points behind Juventus who occupy the final Champions League spot after losing at Atalanta.
Inter had won their last 11 games in a seeming relentless march to the Serie A title but this game had always threatened to be a tricky encounter.
Eriksen’s influence in Inter’s success has been negligible but there were shades of his old self with a fine leveller, drilled in after Napoli failed to deal with a swift counter-attack.
Inter survived two late scares – first Matteo Politano rattled the crossbar and then the referee consulted the pitchside monitor to correctly overturn his penalty decision against a strong challenge by Stefan de Vrij.
Conte’s side now need just 13 points from seven games to become champions, despite closest challengers Milan earlier claiming a narrow win over Genoa.
Ante Rebic’s opener for Milan had been cancelled out by former loanee Mattia Destro but Gianluca Scamacca’s unfortunate own goal enabled Milan to close the gap at the top to nine points.