But they dropped crucial points to slip four behind Inter Milan, who won 2-0 at Atalanta where Carlos Augusto and Lautaro Martinez scored.
Napoli nearly struck early when Giacomo Raspadori rattled the post, while McTominay forced lonu Radu into fine saves.
At the other end, Kike Perez and Daniel Fila had fine chances before Romelu Lukaku's header was kept out by Radu's top stop.
Juventus boss Thiago Motta refused to quit despite his side suffering their first back-to-back Serie A defeats in over a year with a 3-0 humbling by Fiorentina.
Following last week's 4-0 drubbing by Atalanta, they went behind to Robin ...