Saturday night saw the Giallorossi beat Inter Milan to win a seventh game in a row, leaving title rivals Napoli and reigning champions Juventus both five points adrift.
But after Goran Pandev made the early breakthrough in Naples, further goals from Gokhan Inler and Jose Callejon guaranteed the Azzurri would close to within two points of the capital club before Marek Hamsik added a fourth at the death.
Livorno, to their credit, refused to lie down and the spirit that has so far guided the promoted club into mid-table almost saw them spoil Pepe Reina's clean sheet through the impressive Innocent Emeghara on the stroke of half-time.
Napoli coach Rafael Benitez now has two weeks to formulate a game plan that will halt Roma's blistering start, as the sides meet at the Stadio Olimpico on October 19.
The Spaniard's men knew they could not wrest back first place before the international break but they wasted no time reasserting their title credentials.
It took just three minutes for Pandev to dance on to Dries Mertens' assist from a deadly counter-attack and slam the ball past Francesco Bardi.
Livorno responded brightly, though, lifelong Napoli fan Pasquale Schiattarella squeezing into the box only for Federico Fernandez to make the block.
Pandev then came knocking again after leaving a dizzy Leandro Rinaudo on the ground, but his finish sailed over the crossbar.
In the 26th minute, Inler doubled the hosts' advantage, the Swiss midfielder picking up Mertens' short pass to pick his spot from 30 metres.
Bardi did get his gloves to the ball but it slipped out of his grasp and into the net.
Azzurri goalkeeper Reina, who had been a non-paying spectator for most of the first half, was caught unawares four minutes before the break.
Emeghara perhaps deserved a goal from a perfectly-executed volley from outside the area, but the beaten Reina's blushes were spared as the ball slammed into the angle of post and bar.
Despite their bad luck in front of goal Livorno had certainly shown pluck at the San Paolo, so it was unfortunate when they conceded a third goal nine minutes after the interval.
This time Pandev turned provider, his dainty through-ball to Callejon preceding a scuffed shot from the Spanish winger which confounded Bardi nevertheless.
The on-loan Inter keeper endured a one-sided afternoon but did pull off a stunning save on Mertens' free-kick in the 67th minute.
Early protagonists Pandev, Callejon and Emeghara were withdrawn as time ticked away but Inler remained and hit a post with another effort from distance.
Hamsik, however, did manage to make a late impact before being replaced by Davide Bariti.
The game was already won in the 88th minute but the Slovakian schemer was well-placed to convert Federico Insigne's spilled shot after Livorno had failed to properly deal with a corner.