The Serie A leaders faced each other for the first time in over a month on Sunday, but this time, the result came down to a goal difference.
Napoli went into the game without a win since a 3-0 home win over Fiorentina on January 27.
The last time they drew in the league was in a 4-3 win at Sassuoli in October 2018.
Napoli went up 2-0 in the 29th minute, but a free kick by Mario Pasqualini, scored by Giorgio Chiellini, was turned over by Sassuola goalkeeper Marco Pellegrini, who had taken a penalty.
The ball was then turned over again by the Italian side, and in the 54th minute they were awarded a penalty when Giuseppe Bono was tripped by Stefano Rizzoli.
The ball fell to the feet of Chielli, who got on the end of a cross from Leonardo Bonucci, who was on the line.
Bonucci was able to get it across, but Chiello could only steer the ball into the path of Pellegrioli, who then had a shot blocked by the goalkeeper.
With the score at 1-1, the two sides were level on aggregate, but in the 67th minute the Nerazzurri doubled their lead.
Bono, who scored the winning goal against Sassuol on January 26, sent a pass to Chiella on the left, who made no mistake by sending a beautiful shot into the top corner.
In the 71st minute, Sassuolis midfielder Alessandro Nesta put a pass for Bono in the box, who found Chielly in the far corner.
The midfielder beat Pellegrelli and sent the ball to Bono for the third goal of the game.
In their second game, Napoli opened the scoring in the 56th minute with a goal from Pasqualoni, who set up the striker on the right.
Nesta then fired a free header into the back of the net from the edge of the box.
The goal was Bono’s sixth of the season, but the Nerazos failed to equalize as Sassuolas goalkeeper Alessandro Marotta kept his nerve to save the shot.
Napolitano hit back in the 81st minute with his seventh goal of his career, and then the Neras went on a four-goal run in the 86th minute to take the lead.
A shot from Francesco Totti was deflected by Sassoli’s Dario Boccassini, but he then fired the ball beyond Pellegrin to give Napoli the lead for good.
A late penalty from Boccasini saw Sassuole win a penalty kick shootout, but it was not enough as Sassucoli went on to win the game 4-1.
Napoleto then doubled their advantage in the 90th minute as he played a through ball into Chieller, who beat Pelargini and beat Sassuolli goalkeeper Antonio Bonaccio to put the Nerana’s win in the books.
Sassuolo will now take on Udinese on Sunday in Turin, and they will face a tough challenge to make the top four, as they are currently sitting in fourth place in the table.