Napoli fell four points behind Juventus once more after falling to a Giovanni Simeone hat trick and a 3-0 win at Fiorentina.
Defender Kalidou Koulibaly was given a straight red after just six minutes for a last-ditch foul on Simeone and his side never recovered.
After just 10 minutes – to deal with his defender’s dismissal – boss Maurizio Sarri was forced into swapping midfielder Jorginho for defender Lorenzo Tonelli.
But the reinforcements could not help the visitors stop the son of Atletico Madrid manager Diego Simeone from opening the scoring.
The 22-year-old was fed down the left wing and he fired a low left-footed shot through the legs of former Liverpool goalkeeper Pepe Reina.
And, with 62 minutes on the clock, the chip-off-the-old–block grabbed his second of the night to get the party started 250 miles away in Turin.
A clever corner from the Florence club found the Argentina U23 ace free and he swept the ball home with his right foot to deflate Napoli completely.
After everything that has gone in this Scudetto race – even just yesterday – of course it would have to be Fiorentina, the team whose fans hate Juventus the most, who serve it up to them on a plate by beating Napoli.
— Paolo Bandini (@Paolo_Bandini) April 29, 2018
The former River Plate finisher completed his amazing treble with the last kick of the game.
Juve were on the floor with three minutes of their clash with Inter left on Saturday as they trailed 2-1.
But an own goal and a Gonzalo Higuain strike turned the game around and left Napoli the chance to reduce it to one point with their game in hand – and they blew it.