Lazio's hopes of forcing their way into contention for one of Serie A's European berths were dented this evening courtesy of Sassuolo, who claimed all three points at the Stadio Olimpico thanks to goals from Domenico Berardi and Gregoire Defrel.
It means that Stefano Pioli's men have won just three of their 10 league matches in 2016, which has left them eighth in the table.
Sassuolo, meanwhile, are now four points ahead of their hosts following their second win on the bounce.
The deadlock was broken in Rome four minutes before the break when Lazio's Mauricio was penalised for a foul inside the area and Berardi stepped up to fire in his sixth goal of the campaign from the spot.
Playing on the counter-attack after the restart, the away side went on to double their advantage in the 67th minute.
A cross from Nicola Sansone picked out Defrel and having taken one touch to fashion out a chance, the 24-year-old then lashed his shot beyond the reach of Lazio goalkeeper Etrit Berisha.
The home side's best chance of reducing the arrears fell to former Germany international Miroslav Klose soon after, but his header was palmed to safety by Andrea Consigli.
