Inter’s position on top of Serie A is at risk after a 1-1 draw against Atalanta.
Lautaro Martinez put Inter ahead after four minutes in the San Siro only for Robin Gosens to pull Atalanta level on 76 minutes.
Atalanta striker Duvan Zapata got his first start after a long injury layoff but Inter were struggling without suspended Nicolo Barella and injured duo Matias Vecino and Alexis Sanchez.
Good work by in-form Inter strike duo Martinez and Romelu Lukaku paved the way for the first goal minutes into the game.
But Gosens volleyed in with quarter of an hour to go and Inter goalkeeper Samir Handanovic saved a Luis Muriel penalty two minutes from time to hold onto a point.
Atalanta are fifth, equal on points with Roma, who occupy the final Champions League berth.
Lazio extended their winning streak to a club record of ten games as they inflicted a second consecutive defeat on Serie A runners-up Napoli thanks to a blunder from goalkeeper David Ospina with eight minutes to go.
Colombian international Ospina was caught in possession inside his own box allowing Immobile to tap in his 20th goal in 19 games to the delight of the home crowd as the club marked their 120th anniversary.
“What is missing for the Scudetto? To be honest, we’re not missing much,” said coach Simone Inzaghi.
“We keep conceding crazy goals,” said Napoli coach Gennaro Gattuso whose side drop to tenth place.