Napoli moved 18 points clear at the top of Serie A with a routine victory at mid-table Empoli.
An own goal by Empoli defender Ardian Ismajli broke the deadlock before Victor Osimhen made it 2-0 with his 19th league strike of the season.
Portugal left-back Mario Rui was sent off in the second half for lashing out at Francesco Caputo, but Luciano Spalletti’s side held on comfortably.
Inter can reduce the gap to 15 points again at Bologna on Sunday.
Osimhen has now scored in his last eight Serie A games, becoming the first player to do so since Cristiano Ronaldo – who netted in 11 consecutive matches for Juventus.
The Nigeria forward had the ball in the net again in the second half but the goal was ruled out for offside earlier in the move.