Trailing at half-time to Milan Djuric's early header and loudly barracked by protesting away fans, champions Napoli roared back to win following sumptuous strikes from Victor Osimhen, Matteo Politano and Piotr Zielinski in six second-half minutes.
Andrea Colpani's deflected strike closed the gap to one seconds after Zielinski's first goal since October, but Giacomo Raspadori added the fourth in the 69th minute to ensure Napoli moved up to seventh.
Francesco Calzona's side will hand over their league title, almost certainly to Inter Milan, at the end of the season and are 10 points behind Bologna who currently sit fourth and in the last Champions League spot.
However, Serie A is leading the race for an extra place in next year's revamped tournament, meaning fifth could be good enough.
Roma are three points behind Bologna in fifth after beating local rivals Lazio 1-0 for the first time in over two years on Saturday.
Two points ahead of Napoli in sixth are Atalanta who are at Cagliari later on Sunday and also have another game in hand to play with Fiorentina before the end of the season.
Osimhen drew Napoli level in the 55th minute with a towering header which briefly left the Nigeria forward in agony on the ground after landing awkwardly following his huge leap over Armando Izzo.
Two minutes later, Politano scored one of the goals of the season to put Napoli ahead, volleying home an unstoppable dipping shot from distance.
And Monza goalkeeper Michele Di Gregorio was left punching the air in frustration after failing to move for Zielinski's long-range rocket which crashed in off the crossbar.
And Raspadori netted just 21 seconds after replacing Khvicha Kvaratskhelia to seal a rare convincing win for Napoli in a troubled campaign.
Bologna held
Thiago Motta's Bologna would have moved above Juventus with a win at the Stadio Benito Stirpe but instead are a point behind the Turin giants after a below-par display.
Bologna almost snatched what would have been an undeserved win in the final seconds when Stefano Turati tipped Dan Ndoye's close-range finish onto the bar before Ndoye then scooped over the rebound in front of an open goal.
"Nobody would have imagined us being in this situation at the beginning of the season," Motta told reporters.
"We're not even looking at the table because we have a lot of games left between now and the end of the season."
Juve, on a dreadful run of form which has seen them pick up just seven points from their last nine league fixtures, host Fiorentina in Sunday's late match.
Bologna are aiming to reach the Champions League for the first time and are a good bet to do so thanks to eight wins from their last 10 matches.
Although Bologna played one round in the old European Cup in 1964, the same year that they most recently won Serie A, they have never participated in the modern Champions League.
Frosinone dropped into the relegation zone on Saturday night after Empoli's last-gasp 3-2 win over Torino and a point was not enough to exit the bottom three.
Eusebio Di Francesco's side, who won Serie B last season, are two points from safety after 10 matches without a win.
