Increasingly inconsistent before the turn of the year, La Dea are in seventh place, while Roberto De Zerbi's visitors ended 2020 with all three points against Sampdoria to sit fourth - just above traditional giants Napoli and Juventus.
Atalanta enter this year as they ended the last - with doubts over the future of their talismanic captain Papu Gomez hanging grimly over a previously tight-knit squad.
The irrepressible Argentinian playmaker has been ostracised by manager Gian Piero Gasperini since a mid-December falling out between the pair and looks set to soon depart for one of the nearby Milan clubs.
Just before Christmas, a Gomez-less Nerazzurri let slip a probable win against Bologna after an early brace by erstwhile supersub Luis Muriel - their leading scorer in Serie A with seven goals, despite rarely starting - to draw 2-2 at Dall'Ara.
Having previously sparkled in the thumping of Roma, with the returning Josip Ilicic and striker Duvan Zapata to the fore as flying wing-back Robin Gosens also netted his third goal of a productive season, it was a frustrating end to a frequently spectacular 12 months.
After a fairly subdued November - with only two points from three league games - Atalanta collected eight points from their four December fixtures to stay in touch with the top six in Serie A.
Welcoming high-flying Sassuolo to the Gewiss Stadium on Sunday though, perhaps Gasperini's chief concern should be how to improve a seriously leaky defence to keep the visitors' potent attack at bay.
However, his front-foot principles are unshakable and promise to take La Dea's tifosi for another entertaining ride again this year.
Sassuolo's current fourth place in the standings represents their best-ever ranking after the first 14 rounds of a Serie A season and reflects a superb start to the 2020-21 campaign for De Zerbi's side.
After having failed to win against either Fiorentina or Milan, the Neroverdi saw off Sampdoria just before Christmas, with a 3-2 win at Marassi.
That game marked a return to goalscoring form for Sassuolo, as the Emilian side had begun to show the effects of being without injured star striker Francesco Caputo for an extended period. The well-travelled forward was the most accurate Serie A marksman of 2020 - finding the net on average once every 3.2 shots on goal.
Last year's club top scorer, with 21 strikes in Serie A and now six in the current campaign, Caputo should be fully fit to resume racking up goals and leading the Sassuolo line with characteristic aplomb.
The long-time strike partner of 'Ciccio' has been fellow Azzurri forward Domenico Berardi, who can boast a record of seven goals and four assists so far. Between them, the prolific pair should prove more than a match for Atalanta's fragile defence on Sunday.
Atalanta BC Serie A form: DLWDWD
Atalanta BC form (all competitions): DWWDWD
Sassuolo Serie A form: LDWDLW
Young Hamed Traore will deputise for Djuricic if De Zerbi does not want to risk his returning Serb star from the start, with Jeremie Boga and Berardi also comprising the three-man supply line for Ciccio Caputo.
Atalanta BC possible starting lineup:
Gollini; Palomino, Romero, Djimsiti; Hateboer, De Roon, Freuler, Gosens; Pessina, Ilicic; Zapata
Sassuolo possible starting lineup:
Consigli; Toljan, Chiriches, Ferrari, Kyriakopoulos; Locatelli, Lopez; Berardi, Traore, Boga; Caputo
We say: Atalanta BC 2-2 Sassuolo
These two entertaining outfits are hard to separate and both are often admired for their progressive approach to Calcio.
With the home side far from defensively sound, it is probable that Sassuolo can steal away from Lombardy with at least another point added to their club-record total so far, while Atalanta can look ahead to easier games with Parma, Benevento and Genoa later this month.