Separated by only one point in the Serie A standings, the sides have experienced contrasting fortunes over the past fortnight.
Thursday's Coppa Italia success over Parma was the fourth straight win for Lazio - a run which includes their crushing 3-0 defeat of arch-rivals Roma - with the concession of just two goals.
Still undefeated this year, Simone Inzaghi's side are now beginning to resemble the all-conquering unit which took Serie A by storm throughout much of the 2019-20 campaign.
Largely thanks to the efforts of European Golden Boot-winner Ciro Immobile, who has already bagged 12 goals in 15 outings during an illness-disrupted season, the Biancocelesti have racked up 30 goals at the Olimpico to date; never failing to score at least once on home turf so far.
Immobile has found the net in seven of his nine league games played since the start of December - a golden period that has seen his club catch up ground lost during a difficult autumn spell.
Lazio are now just three points away from third place in a tightly-contested top half of the table and will face both Atalanta and Inter Milan in the coming weeks, after taking on Sassuolo.
Having booked a cup quarter-final in Bergamo next Wednesday and destroyed Roma in the Derby della Capitale, the Aquile will now look to cap an excellent week's work with victory over their Emilian visitors on Sunday.
Another season of great promise and progress has stalled just recently for Sassuolo, as they crashed out of the Coppa Italia to Serie B side SPAL last week and have picked up just one league win since the turn of the year, after a disappointing draw with Parma last time out.
Nonetheless, the Neroverdi have registered a healthy tally of 30 Serie A points so far this term, with their club record in the first half of a top-flight campaign currently standing at 31 in 2015-16.
Five forthcoming fixtures against teams currently placed 12th or below should certainly set them up for a positive start to the second half of the campaign, but first they must travel to Rome for a stern test of their credentials.
Roberto De Zerbi's team have lost their last two away league games - though earned an impressive five wins and two draws from their previous seven on the road - and will now take on Lazio without the help of their outstanding performer.
Since they were promoted to Serie A, Sassuolo have earned an average of 1.4 points in matches when star striker Domenico Berardi has featured, compared to 0.9 when he has not played - a clear demonstration of the Azzurri forward's importance to the team, which is comparable to that of Immobile for Lazio.
As their current top scorer (with seven goals so far) remains out through injury, others will need to take up the slack against a much-improved Biancocelesti back line on Sunday.
Lazio Serie A form: WLDWWW
Lazio form (all competitions): LDWWWW
Sassuolo Serie A form: LWLWLD
Sassuolo form (all competitions): WLWLLD
Simone Inzaghi has received mixed news on the injury front, as Mohamed Fares and Joaquin Correa safely returned to action in midweek, but key midfielder Luis Alberto (appendicitis) and centre-back Luiz Felipe - with an ankle injury that will reportedly sideline him for several months - are ruled out for Lazio.
Danilo Cataldi is still unavailable too, so Jean-Louis Akpa Akpro should join Lucas Leiva and Sergej Milinkovic-Savic in midfield, with Correa set to start alongside regular partner Ciro Immobile up front.
Both Domenico Berardi and Mehdi Bourabia have thigh injuries, while winger Jeremie Boga and midfield regulator Maxime Lopez are doubtful. In Berardi's absence, Francesco Caputo should be backed up by Gregoire Defrel and Hamed Traore in attack.
Lazio possible starting lineup:
Reina; Radu, Patric, Acerbi; Lazzari, Milinkovic-Savic, Leiva, Akpa-Akpro, Marusic; Correa, Immobile
Sassuolo possible starting lineup:
Consigli; Toljan, Marlon, Ferrari, Rogerio; Magnanelli, Obiang; Defrel, Djuricic, Traore; Caputo
We say: Lazio 2-0 Sassuolo
A clear sense of momentum is definitely building in the Lazio camp, with an admirable series of wins since the start of the year.
Considering, too, several injury absences suffered by a thin Sassuolo squad, the Aquile's increasing defensive solidity should provide the platform for them to spring their attack-focused opponents on the break.