Kalidou Koulibaly was sent off early as Napoli succumbed to a Giovanni Simeone hattrick in a shock 3-0 defeat at Fiorentina that edged Juventus closer to a seventh successive Serie A title on Sunday.
With just three games left, Juventus have a four-point lead on closest challengers Napoli and could wrap up yet another 'Scudetto' next weekend.
Koulibaly, labelled a hero when he scored the last-gasp header that kept Napoli's ambitions alive with a 1-0 win over Juventus in Turin last week, turned villain in Florence after he was sent off after just eight minutes.
Argentina forward Simeone -- the son of Atletico Madrid boss Diego Simeone -- scored all three goals in a spectacular display to keep Fiorentina's Europa League hopes alive.
Juventus battled past 10-man Inter Milan in a San Siro thriller on Saturday to prevail 3-2 thanks to two late goals in three minutes. Massimiliano Allegri's champions host Bologna on Saturday and will be assured of a seventh straight title if Napoli fail to win at home against Torino on Sunday.
Napoli never recovered from Koulibaly's expulsion, the towering Sengalese defender inititally shown a yellow card for kicking out at Simeone as he charged towards goal. But a video assistant referee (VAR) review at the Stadio Franchi in Florence upgraded the yellow to red, with a free-kick given instead of a penalty.
Napoli coach Maurizio Sarri replaced midfielder Jorginho with central defender Lorenzo Tonelli. But Napoli struggled to contain their rivals, Simeone breaking the deadlock by firing through the legs of goalkeeper Pepe Reina after 34 minutes.
Simeone pounced to fire in the second on 62 minutes after the ball initially bounced off Elseid Hysaj and Reina cleared with his leg. The 22-year-old completed his hattrick three minutes into injury time to claim his 13th goal this season.
"My father will be very happy with the hattrick!" said Simeone as Fiorentina moved to within four points of the Europa League places.
On Saturday's Serie A showpiece, Juventus battled past 10-man Inter Milan with two late goals giving the champions a 3-2 win in the San Siro.
Inter looked as if they would pull off an unlikely victory as the hosts led until three minutes from the whistle despite playing more than 70 minutes a man down after Matias Vecino was sent off. But Milan Skriniar turned the ball into his own net after 87 minutes with Gonzalo Higuain heading in the winner two minutes later.
"I have to congratulate the lads, it was an important step towards the Scudetto," said Juventus coach Massimiliano Allegri. "It was a beautiful night of football between two teams who had to win. Winning at San Siro is very complicated, they did very well at 10. We know that to win the championship we have to win all of our games."
Juve's lead had been cut to one point after their defeat by Napoli in Turin last week.
Maurizio Sarri's Napoli travel to Fiorentina on Sunday bidding to match the champions and keep their push for a third title after 1987 and 1990 alive.
Saturday's defeat damages Inter's hopes of Champions League football next season as they stay fifth behind with just three games to play.
"It will be hard to put this defeat behind us," said Inter coach Luciano Spalletti. "This match meant a huge amount to us and the team deserved a different result."