The midweek loss at lowly Lecce appeared to signal the end of Lazio's title challenge, but Juve's implosion en route to a 4-2 defeat by AC Milan kept the gap at only seven points.
But a third straight loss for Lazio means that when Juve host in-form Atalanta later on Saturday, Juve could either stretch their lead or the Bergamo outfit could climb into second.
Lazio were only one point behind Juventus when the Italian top flight resumed following the coronavirus lockdown, but they have been beaten four times in six matches since.
Atalanta, on a winning streak of 11 games in all competitions, could cut the gap to Juve to six points if they beat the Turin giants at the Allianz Stadium.
A fourth successive league win for Sassuolo boosted their European hopes as they moved within three points of seventh-placed Milan, who occupy the final possible Europa League spot.
Hosts Lazio survived an early scare when Sassuolo striker Giacomo Raspadori was denied an early goal for offside.
But Simone Inzaghi's men grabbed the lead against the run of play 12 minutes before half-time as Alberto's blocked shot bounced back off his shin and looped into the top corner.
It was the former Liverpool midfielder's seventh goal of the season in all competitions.
But Sassuolo continued to be the better side and deservedly levelled seven minutes into the second period as Mehdi Bourabia won the ball high up the pitch and fed Caputo, who squared for the 20-year-old Raspadori to cap his first Serie A start with a simple tap-in.
Lazio rarely looked like grabbing an all-important victory, with centre-back Bastos coming closest to a late winner for the home side when he headed over as the capital club finished the match with just one shot on target.
They always looked vulnerable at the back, though, and Caputo pounced to nod home in the second minute of injury-time after the Lazio defence fell apart after failing to clear a corner.