The teams convene in Bergamo, with the hosts suffering back-to-back defeats before the international break and their visitors yet to win a league game under Raffaele Palladino.
Match preview
Including their UEFA Super Cup loss to Real Madrid last month, Atalanta have come away empty-handed from three of their first fixtures this season, following a turbulent summer in the transfer market.
Gian Piero Gasperini's side began the 2024-25 campaign with a win against Lecce, but two failures against Torino and Inter Milan were to follow - and the latter loss was particularly chastening.
Within 10 minutes of kickoff at San Siro, the Europa League winners were two goals down and staring at defeat to their Lombardy rivals, and by the final whistle they had conceded four times without managing a response.
Having secured another top-four finish last term and claimed the club's first-ever European trophy, Gasperini agreed to extend his stay in Bergamo, but Teun Koopmeiners then forced his way through the exit - and Ademola Lookman almost followed him - while star striker Gianluca Scamacca was struck down by an ACL injury.
After some frantic pre-deadline recruitment, Atalanta now reconvene after the international break, to begin the task of rebuilding some confidence before their return to the Champions League; Arsenal will be their first opponents next week.
The Nerazzurri have lost as many as three of their first four Serie A matches only once in the Gasperini era, back in 2016, and are intent on avoiding that fate this weekend, when they seek some revenge for last season's double defeat to Fiorentina.
Including a delayed season finale - as the teams played out a previously postponed fixture in early June, due to both taking part in UEFA finals - Fiorentina beat Atalanta 3-2 twice last term.
However, La Dea came out on top in the clubs' Coppa Italia semi-final before going on to taste European glory in Dublin, while the Viola had to absorb another Conference League final heartbreak.
Vincenzo Italiano then stepped aside, having come so close to claiming some elusive silverware for the Tuscan side, but new boss Raffaele Palladino has yet to get Fiorentina fully firing.
Only a stoppage-time equaliser from recent arrival Robin Gosens staved off defeat to Palladino's old club Monza just before international football intervened, and the Viola are yet to win in 2024-25.
Indeed, their only success so far came via a penalty shootout in last month's Conference League playoffs, after two draws with Puskas Akademia sent that tie down to spot-kicks.
Fiorentina may have drawn their first five games in all competitions for the first time ever, but - stretching back to the tail-end of last season - they have also lost just one of their last 11 in Serie A.
Atalanta BC Serie A form:
Fiorentina Serie A form:
Fiorentina form (all competitions):
Team News
Atalanta's long list of absences has reduced a little of late, as defensive duo Isak Hien and Sead Kolasinac could return on Sunday, and Nicolo Zaniolo may make the bench.
However, Berat Djimsiti is still struggling with a muscular problem, while Giorgio Scalvini and Gianluca Scamacca are both unavailable for the long term due to ACL injuries.
With Scamacca sidelined and Ademola Lookman out of favour since events during the transfer window, summer signings Marco Brescianini, Lazar Samardzic and Mateo Retegui could join forces in the final third.
Lookman's recall is not out of the question, though, and Charles De Ketelaere is also in contention; meanwhile, former Bayer Leverkusen centre-back Odilon Kossounou should make his debut in defence.
Fiorentina are close to a fully fit squad, as Albert Gudmundsson is back in full training after overcoming a calf injury that has blighted his start to life in Florence.
Ex-Atalanta wing-back Robin Gosens returns to Bergamo this weekend, starting on the left flank of a 3-4-2-1 formation spearheaded by revived Italy striker Moise Kean.
Fellow new boys Yacine Adli, Edoardo Bove, Amir Richardson and Danilo Cataldi are all fighting for places in midfield, while high-profile goalkeeper David de Gea is still duelling for first-choice status with Pietro Terracciano.
Atalanta BC possible starting lineup:
Carnesecchi; De Roon, Hien, Kossounou; Bellanova, Ederson, Pasalic, Ruggeri; Brescianini, Samardzic; Retegui
Fiorentina possible starting lineup:
De Gea; Martinez Quarta, Pongracic, Biraghi; Dodo, Cataldi, Mandragora, Gosens; Colpani, Sottil; Kean
We say: Atalanta BC 2-1 Fiorentina
It will surely be an entertaining encounter at the Gewiss Stadium, as these clubs shared 10 goals in two games last season and have started off on the front foot this term.