Pedro Obiang's red card just before half-time gifted Juve an extra man for the second half but, after taking the lead through Danilo, they were pegged back by Gregoire Defrel's equaliser.
The result means Juve find themselves seven points behind leaders Milan and four behind second-placed Inter ahead of the Derby d'Italia next weekend.
So who were the best and worst players on the pitch?
✔️ GOOD PERFORMANCE
Danilo was an unpopular figure with supporters last season after arriving from Manchester City in a swap deal involving Joao Cancelo.
However, he has surprisingly been one of Juve's best players this campaign and he broke the deadlock on Sunday with a ferocious long shot into the bottom corner.
He also provided the assist for Ronaldo's third goal as he proves to be a crucial player tactically in Andrea Pirlo's 3-5-2 / 4-4-2 hybrid.
You can never keep the great man down. It had seemed to be one of those nights where nothing was going to come off for Ronaldo.
He'd had a game-high six shots and 15 touches in the box, he'd been denied three times by Sassuolo's goalkeeper Andrea Consigli, and he had missed a sitter from just yards out.
But Ronaldo never gives up and he clinched a vital win in stoppage time with a clinical run and finish into the bottom corner. He now has 15 Serie A goals for the season, three ahead of the next best Romelu Lukaku.
❌ BAD PERFORMANCE
Paulo Dybala: 5.8
A disastrous evening for the Argentine, who had appeared to be finally clicking into gear when he provided a brilliant assist for Federico Chiesa's first goal against Milan in midweek.
However, nothing went right for Dybala in the first half versus Sassuolo. He was slow, sluggish and made no impact whatsoever on the match. He had no attempted shots, no dribbles and created no chances.
And to make matters worse, he limped off with a knee injury and had to be replaced by Dejan Kulusevski. Having struggled so much this season with physical problems, not to mention the aftereffects of Coronavirus, this is the last setback Dybala or Juventus needed.
⭐ STAR MAN
Aaron Ramsey 8.3
The Welshman picked a big moment to score his first goal of the season, as he made a trademark late run into the box to sidefoot home from Gianluca Frabotta's cross.
Ramsey entered the pitch early in the game after an injury to Weston McKennie and he showed why coach Andrea Pirlo considers him the best option for the advanced midfield role.
The 30-year-old had four shots and an impressive eight touches in the box as he consistently supported the Juve attackers.
He also created two big chances and boasted an impressive pass completion rate of 90 per cent.