Matteo Politano’s late goal keeps Sassuolo in sixth place and mathematically relegates Frosinone, who hit the woodwork twice.
There was so much at stake at the Matusa, as the hosts were desperate to avoid relegation in their debut top flight campaign and the Neroverdi needed a victory to retain sixth place after Milan’s win last night.
Raman Chibsah and Mirko Gori were suspended for Frosinone, who also missed Danilo Soddimo and Luca Paganini. Sassuolo had to do without Luca Antei, Karim Laribi, Emanuele Terranova and Davide Biondini.
The Canarini got off to a very aggressive start and Andrea Consigli needed a desperate early double save from point-blank range on Federico Dionisi.
Bad news for Frosinone, who lost goalkeeper Francesco Bardi to a thigh strain in the opening half-hour, as he left the pitch in tears.
Robert Gucher blasted over the ball and Vasyl Pryyma crucially intercepted an Alfred Duncan through ball for Gregoire Defrel.
Paolo Sammarco saw Consigli flap his effort round the post with cat-like reflexes. Massimo Zappino spilled a Nicola Sansone strike straight after the restart, while Oliver Kragl’s free kick zipped under the wall and forced Consigli into a tricky save.
Francesco Acerbi got on the end of a Domenico Berardi cross, forcing a corner off Pryyma, but Frosinone hit the woodwork with Kragl on the counter, his daisy-cutter clipping the upright.
The Canarini were unlucky again on 75 minutes, as Daniel Ciofani saw Consigli off his line and the audacious lob thumped the outside of the far post.
Ciofani tested Consigli again and Diego Falcinelli fired inches wide, but as Frosinone were pouring forward, they were caught out on the counter-attack.
Berardi’s cross went past Falcinelli in the middle, but Matteo Politano turned it back into the net from a tight angle at the far post.
Frosinone were relegated, but the crowd applauded and chanted 'Thank you lads' after the final whistle. The team and opponents Sassuolo returned the applause for this show of sportsmanship, which is sadly rare in Italy.