Earlier in the day Italian veteran Alessandro Del Piero scored a controversial late spot-kick to give out-of-form Serie A giants Juventus a much-needed 3-2 victory over Genoa.
Napoli had the best of Sunday night's game at the San Paolo stadium, hitting the woodwork twice to Inter's once, but the champions held on to extend their lead over Roma to seven points, although AC Milan could cut that to six if they win their game in hand.
Inter coach Jose Mourinho admitted Napoli deserved something from the game but said his side should have had a penalty when a Maicon cross hit Salvatore Aronica's arm in the box in the first half.
"I think the referee was excellent today. If you forget that little big episode in the first half, he did very well," said Mourinho.
"He made a mistake but Napoli didn't deserve to lose."
The draw pushed Napoli back up to fourth and the last Champions League qualification spot although three more teams are within just two points of them.
Napoli coach Walter Mazzarri, whose side have lost only once in 17 league matches under his stewardship, believed they deserved more.
"I'm happy with the way my players played, we deserved to win," he said. "But that's destiny, sooner or later the ball will go in."Napoli had felt hard done by a week ago when they were beaten 3-1 at Udinese by two injury-time goals, having been reduced to 10 men before half-time.
And they began this game like a team eager to make amends with Slovakia midfielder Marek Hamsik smacking a long-range shot against the bar on 10 minutes.
Three minutes later Fabio Quagliarella fired into the side netting when left free at the back post.
Inter goalkeeper Julio Cesar was then the hero on 19 minutes with a stunning reaction save to deny German Denis's flying header from Hamsik's right-wing cross.
The visitors did have their moments and on the half hour Sulley Muntari caught the ball sweetly on the half-volley just outside the area and he too thudded the woodwork.
Inter forward Goran Pandev should have done better when set free in the area by McDonald Mariga after the break but he shot too close to Morgan De Sanctis.
Diego Milito than forced the Napoli stopped into a save at his near post and Walter Samuel headed over the bar.
But back came Napoli and Quagliarella hit a daisy-cutter against the post on 65 minutes only for Denis to woefully skew the rebound high and wide with the goal at his mercy.
Napoli kept pushing and Hamsik was left kicking himself after firing wide from Denis's knock-down when promisingly placed 11 minutes from time. In Turin, 35-year-old Del Piero scored a brace while Brazilian striker Amauri added the other as the Old Lady came from behind to record only their fourth win in 15 matches in all competitions and give coach Alberto Zaccheroni his first win in the three matches he has been in charge.
But Genoa were furious that Juve were awarded the 78th-minute penalty that proved decisive.
"From where I was I didn't see it, but I've been told that it was offside, it was outside the area and it wasn't a foul," complained Genoa coach Gian Piero Gasperini.
"There's at least one mistake and maybe three, all in the same action."
Juventus coach Zaccheroni admitted the incident had occurred outside the area.
"I agree that it was outside the area but it's always difficult for the referee to see in these cases," he said.
Genoa took an early lead in Turin through club captain Marco Rossi, but Amauri's 42nd-minute headed equaliser from Mauro Camoranesi's cross drew Juve level.
The hosts took the lead just after the hour mark as Diego's delicate backheel split the Genoa defence allowing Del Piero to score his 271st goal for the club.
However, they had barely stopped celebrating before the game was level again as Rossi struck for a seocnd time.
Juventus, though, had the last laugh as Del Piero tumbled under a challenge and got up to convert the penalty for 3-2.
New boss Edy Reja had an immediate impact at Lazio as they climbed out of the relegation zone with a 2-0 win at Parma