Parma extended their club record unbeaten streak to 14 games thanks to a Marco Parolo strike on two minutes. The Crociati remain on course to challenge for a Europa League place.
Meanwhile, Sassuolo sunk to a seventh consecutive defeat and had Domenico Berardi sent off for violent conduct. Alberto Malesani is still looking for his first points since taking charge of the Neroverdi, who remain at the foot of Serie A.
Malesani came face to face with the side he coached between 1998-2001. Berardi was dropped from the starting lineup for the second game in succession, amidst rumours of an internal bust-up with his coach. Pedro Mendes, Paolo Cannavaro, Marcello Gazzola and Sergio Floccari all faced their former club.
Parma were unchanged from the 2-2 draw with Fiorentina, although Gianni Munari was suspended after his dismissal as a late substitute in Monday's game. Afriyie Acquah returned to the bench after completing a ban. Heavy rain led to standing puddles all over the pitch, making it hard to string passes together.
Parma found the net with exactly a minute on the clock. Sassuolo were caught cold when Jonathan Biabiany crossed for Parolo to slot into the far corner from six yards. There was a suspicion of offside on Biabiany, but the goal was allowed to stand.
Biabiany and Antonio Cassano combined to send a dangerous ball into the box, but Amauri sent his downward header wide. Lucarelli turned in a Cassano cross on 14 minutes, but the Parma captain was adjudged to be offside.
Raffaele Pucino saw a free kick deflect off the Parma wall and go over the bar, while Amauri curled a volley inches past the post.
Simone Zaza found himself sandwiched between the Parma defence as he made a run at goal. The frontman was angry not to be awarded a free kick and was booked for dissent by the referee. The frontman will now miss next weekend's crunch relegation clash away at Bologna.
On the stroke of half time, Amauri got on the end of a slick passing move to stretch and direct a shot inches wide of the post. The ground staff worked diligently during the break to lift some of the water from the pitch.
Parma wasted a golden chance to double their lead midway through the second half. Gargano picked out Cassano, who chested the ball down in the box, only to send a tame shot straight at Pegolo.
Antonio Mirante was finally called into action and made two impressive stops to preserve Parma's lead. The goalkeeper was at full stretch to divert Gazzola's curler past the far post. From the resulting corner, Mirante fisted away a vicious bicycle kick from Cannavaro, then sprung back up to stop Antonio Floro Flores putting in the rebound.
Sassuolo could sense the balance of the game turning in their favour. Malesani brought on Berardi, but the 19-year-old was on the pitch barely a minute when he was caught swinging an elbow at Christian Molinaro's head. The referee sent Berardi off for intent and a lengthy ban now looks likely.
Lorenzo Ariaudo cleared a Lucarelli header off the line, but Mirante continued to thwart the ten men of Sassuolo. Floro Flores controlled a cross in the box and Mirante did well to stop the substitute's rocket going in at the near post.
In the closing minutes, Pegolo parried from Parolo. Ezequiel Schelotto put the ball back across the box, but it evaded the feet of Biabiany.
Sassuolo: Pegolo, Mendes, Ariaudo, Cannavaro, Pucino, (Berardi 71) Magnanelli, Gazzola, Biondini, Brighi, (Marrone 46) Floccari, Zaza (Floro Flores 60)
Parma: Mirante, Lucarelli, Cassani, Paletta, Molinaro, Gargano, Marchionni, (Acquah 68) Parolo, Biabiany, Amauri, Cassano (Schelotto 70)
Goals: Parolo 2 (P)
Sent off: Berardi 72 (S)