Until Saturday's clash in Naples, impressive Sassuolo had gone unbeaten against five of this season's title challengers having claimed wins over Napoli, Juventus and Inter and drawn with Roma and Fiorentina.
But Higuain, who is well on his way to this season's Capocannoniere (top scorer) award, did brilliantly to give Napoli a 42nd minute lead after Jose Callejon's 19th minute header cancelled out Diego Falcinelli's opener from the spot.
Higuain came close twice early in the second half and, just as Napoli were hanging on to a 2-1 lead, the Argentine beat Andrea Consigli with a fierce shot from inside the area in the third minute of added-on time to wrap up the win and maintain his personal quest.
Napoli's 13th win of the campaign leaves them top on 4423 points with a four-point cushion on Inter, who scraped a 1-1 draw away to Atalanta to drop points for the second consecutive match after last week's defeat to Sassuolo.
It means champions Juventus, in third at five points off the pace, can move back up to second and two points clear of Inter with a win away to Udinese on Sunday.
Napoli had the worst possible start at a packed San Paolo, Nicola Sansone earning an early penalty after being fouled by Raul Albiol and Diego Falcinelli stepping up to wrong-foot Pepe Reina in the Napoli goal after just three minutes.
If memories of Napoli's defeat to Sassuolo on the opening season floated back, they were soon put to rest as Napoli replied in positive fashion.
When Insigne ran half the length of the pitch to set up Higuain the Argentine's drive sailed off target while under pressure.
The threat of pacey front man Insigne finally came good on 19 minutes when he got deep, waited for Callejon's call and watched as the Spaniard flicked a near post header past Andrea Consigli to claim his first league goal of the season.
Napoli immediately took the momentum, and although Reina had to look sharp to palm Matteo Politano’s angled drive to safety the hosts saw Insigne hit the upright with a curler after he had nutmegged a defender.
The stadium erupted three minutes before half-time when Higuain put his predator's instincts on display to give the hosts a 2-1 lead, throwing Lorenzo Ariaudo to the ground and off his scent before rushing in to pounce on Hamsik's pinpoint delivery.
Napoli enjoyed a bright start to the second half and twice Higuain came close inside the opening six minutes, his second effort notably flashing inches wide of Consigli's upright.
Insigne came close again when he curled an effort just over, minutes before being replaced by Dries Mertens.
Napoli, however, remained under threat and Reina did well not to panic when he desperately pushed away a cross before seeing a diving header from Lorenzo Pellegrini go wide.
Reina wasn't helping to settle nerves either, the Spaniard scuffing a clearance that he chased down and swept from the feet of Falcinelli 35 metres out from his goal.
But Sassuolo took their eye off the ball, literally, in the final minute of added-on time.
Callejon did well chasing to stop the ball going out of play and found Higuain unmarked inside the area to beat Consigli down low in what was the final kick of the game.
Photo Credits : AFP