The Viola crashed out of the cup in midweek, and are languishing behind Italy's top seven in the league, but their visitors' woes are more substantial.
Match preview
A dramatic climax to Wednesday's second leg in Bergamo saw Atalanta BC progress to next month's Coppa Italia final at Fiorentina's expense, as the Tuscan side let a one-goal advantage from the first leg slip and then fumbled another aggregate lead on the night.
La Dea struck twice during stoppage time, breaking the Viola's hearts after they bravely resisted with only 10 men for most of the second half, following the dismissal of Nikola Milenkovic when the scores were still level overall.
Lucas Martinez Quarta's header put Fiorentina back in front soon after his centre-back partner had seen red, but a late collapse means the Europa Conference League trophy is the only silverware still available to Vincenzo Italiano's cup specialists.
Italiano will leave Florence this summer, with his side struggling to match last season's feats in Serie A, where they sit ninth and are outside contenders for European qualification.
The Viola finally posted their first away win in the top flight since December by beating rock-bottom Salernitana last Sunday, thanks to goals from Jonathan Ikone and Christian Kouame, but they remain unreliable in the final third.
While Fiorentina have won only one of their last five home games against Sassuolo - and the Neroverdi came out on top in January's reverse fixture - they may be confident of adding to two wins from the teams' last three meetings, given their visitors' predicament.
Following three straight draws that stopped them from sinking without trace in the Serie A survival fight, Sassuolo's dismal defeat to Lecce last time out means the prospect of relegation looms large in Reggio Emilia.
After ditching Alessio Dionisi for journeyman coach Davide Ballardini, the Neroverdi have seen little response, and losing 3-0 at home to another struggling side marks a new low.
For just the second time in 11 Serie A seasons, Sassuolo have won fewer than 34 points at this late stage of a campaign - only on their top-flight debut in 2013-14 have they ever fared worse than this term.
Ballardini's side will kick off Sunday's game at least two points adrift of safety, so a return to the second tier is on the cards unless they can engineer a great escape over their final five fixtures.
Having conceded in each of their last 22 away matches before stepping out at Stadio Franchi - a run stretching back to February 2023 - such defensive deficiencies may ultimately prove Sassuolo's undoing.
Fiorentina Serie A form:
D
D
L
L
D
W
Fiorentina form (all competitions):
L
D
D
W
W
L
Sassuolo Serie A form:
W
L
D
D
D
L
Team News
With at least one eye on next week's Conference League clash with Club Brugge, Vincenzo Italiano is sure to rotate a side that played much of Wednesday's game with only 10 men.
Nikola Milenkovic's ban will only apply to next season's Coppa Italia, so aside from minor doubts over Giacomo Bonaventura and Andrea Belotti, Fiorentina's head coach can choose freely from his squad.
Belotti has scored nine league goals against Sassuolo to date, but Lucas Beltran and Christian Kouame are also vying to start as the Viola's central striker.
The visitors, meanwhile are short-handed in attack this weekend, as French forward Armand Lauriente must serve a suspension. He joins Samu Castillejo and star man Domenico Berardi on the sidelines; full-back Marcus Pedersen is also ruled out by injury.
Cristian Volpato and Emil Konradsen Ceide are the main contenders to deputise for Lauriente on Sassuolo's left wing, with long-serving Gregoire Defrel supporting top scorer Andrea Pinamonti up front.
Fiorentina possible starting lineup:
Terracciano; Kayode, Milenkovic, Ranieri, Parisi; Duncan, Lopez; Ikone, Beltran, Sottil; Kouame
Sassuolo possible starting lineup:
Consigli; Toljan, Erlic, Ferrari, Doig; Racic, Boloca; Defrel, Thorstvedt, Volpato; Pinamonti