Roma had the first chance of the game after Mario Hermoso’s header was deflected behind after five minutes, and from that corner, Alexis Saelemaekers unleashed a vicious volley that whistled just past Pepe Reina’s post.
Having survived that scare, Como came close themselves on 18 minutes when Nico Paz’s free-kick evaded the diving Mile Svilar but clipped the crossbar on its way over.
Roma then did have the ball in the net just before the half-hour when Manu Kone ghosted in to finish Saelemaekers’ tempting delivery, but the play was called back for an earlier offside against Stephan El Shaarawy.
Perhaps inspired by his countryman Paz’s effort earlier, Paulo Dybala attempted to beat Reina from a free-kick but the veteran Spanish keeper was alert to keep it out.
Only Como’s next opponents Inter have scored more goals in the opening 15 minutes of the second half this season than Cesc Fabregas’ side, and they came out after the restart on top.
Lucas Da Cunha was the first to test Svilar with a curling effort from a corner before Alieu Fadera stung the Serbian keeper’s palms with a thunderous strike from the edge of the box.
Ex-Roma striker Andrea Belotti couldn’t hurt his former employers, but his replacement, Patrick Cutrone, forced another good stop from Svilar soon after coming on as he flicked Ignace Van Der Brempt’s cross goalbound.
Claudio Ranieri’s side rode out that spell of pressure, and Dybala ought to have punished Como’s wastefulness when shooting from close range, but he could only slide his effort wide of the target.
Much of the traffic for the rest of the game continued to be travelling towards the Roma goal and, just as it looked as though Svilar would save Roma a point, Cutrone’s cutback was prodded home by Gabrielloni in the dying seconds to cue bedlam on and off the pitch.
Roma’s fifth defeat in six Serie A matches was confirmed by Paz at the death, leaving the Giallorossi just two points clear of the relegation zone.