Ending 33 years of hurt, Luciano Spalletti's side eked out a draw with Udinese to finally bring the Scudetto back to Naples; meanwhile, the Viola are enjoying their best form of the season and have a European semi-final to look forward to.
Match preview
Fittingly, the man destined to be this season's Capocannoniere effectively secured an unassailable lead for Napoli at the top of the Serie A standings on Thursday night, as he smashed the ball home to haul his team level in Udine.
Watched by thousands of Neapolitans in the stands of the Dacia Arena and back home at Stadio Maradona - which was packed to the rafters for a screening of the match - the Campanian club became Italian champions for just the third time, by virtue of a tense 1-1 draw.
With 22 goals in 27 league games, Victor Osimhen leads the Serie A scoring charts, sitting three ahead of nearest rival Lautaro Martinez of Inter, and his attacking input has elevated Spalletti's well-oiled machine to top spot.
Despite a recent downturn of fortunes - including last week's 1-1 draw with Salernitana, which forced them to wait a little longer - Napoli have already posted 25 wins and have wrapped up the title with five games to spare.
Before signing off a remarkable season with fixtures against Monza, Inter, Bologna and Sampdoria, the Partenopei now host a side they have scored an average of 2.3 goals per game past in their last eight meetings in Naples, winning five times in the process.
Having inevitably run out of steam towards the end of such a stunning campaign, which also took them to the Champions League quarter-finals for the first time, Napoli have won just one of their last five home games in Serie A.
As their Viola visitors are in fine form, celebrating the club's first Scudetto since 1990 with a win, then, may not be an easy task.
On Wednesday night, Fiorentina also found out how tough Salernitana can be to beat under their former coach Paulo Sousa, as Boulaye Dia followed up his party-spoiling strike at Stadio Maradona last week with a hat-trick in the sides' 3-3 draw in Salerno.
Three times the Viola trailed at Stadio Arechi, and on all three occasions they fought back, as equalisers from Nicolas Gonzalez, Jonathan Ikone and Cristiano Biraghi deprived their hosts of victory.
On the back of last Sunday's 5-0 demolition of Sampdoria, Vincenzo Italiano's men sit eighth in the Serie A standings, but eight points still separate them from the final European place, so their route back into continental competition will surely have to come through the cups.
Fiorentina's Europa Conference League semi-final tie with Basel gets under way next Thursday, and they are also into the Coppa Italia final, where they meet Inter later this month.
Winning either competition would not only see Italiano end the club's long silverware drought, but the Viola would also qualify directly for the 2023-24 Europa League as a bonus.
As they have now conceded three goals in both of their last two away fixtures, the Tuscan club could be forgiven for a similar result from their second straight game down in Campania, as their eyes are wandering elsewhere and Napoli will be out to impress the Azzurri-clad hordes.
Napoli Serie A form:
L
W
D
W
D
D
Napoli form (all competitions):
L
D
D
W
D
D
Fiorentina Serie A form:
W
D
D
L
W
D
Fiorentina form (all competitions):
D
L
L
D
W
D
Team News
Even with the Scudetto secured, Luciano Spalletti - who has become the oldest coach ever to win Serie A - is unlikely to make wholesale changes, as Napoli seek to celebrate in style.
The hosts still have Mario Rui ruled out by an injury sustained in their Champions League exit to Milan, so Mathias Olivera continues to deputise at left-back.
Clearly below his dazzling best of late, Khvicha Kvaratskhelia has neither scored nor provided an assist since the start of April, but he should still start on Sunday, to the left of star striker Victor Osimhen. The Nigerian's title-winning strike in Udine drew him level with George Weah as the top African scorer in Serie A history, and a 47th goal would take him clear of the Liberian president.
Only injured goalkeeper Salvatore Sirigu and suspended centre-back Lucas Martinez Quarta will miss Fiorentina's visit to Naples, so with an almost full squad to choose from, several players could be rotated.
Vincenzo Italiano will want to keep his key men fresh for their first-leg clash with Basel next week, with Nikola Milenkovic also set to replace Martinez Quarta in defence.
Sofyan Amrabat, Luka Jovic and Giacomo Bonaventura are among those contending for promotion from the bench, and the latter has scored five league goals against Napoli to date - though none since 2019.
Napoli possible starting lineup:
Meret; Di Lorenzo, Kim, Rrahmani, Olivera; Anguissa, Lobotka, Zielinski; Lozano, Osimhen, Kvaratskhelia
Fiorentina possible starting lineup:
Terracciano; Dodo, Milenkovic, Igor, Terzic; Amrabat, Mandragora; Kouame, Barak, Saponara; Jovic