Berardi began Sassuolo's fightback in the 15th minute when he rounded Christian Abbiati to score from a narrow angle.
He levelled with a clever half-volley in the 28th minute and completed his hat-trick just before the break when he got between two defenders to fire past Abbiati.
Straight after the re-start, Berardi struck again with a deflected shot to become the first player to score four goals against Milan in Serie A's 85-year history.
Milan dominated the final half hour as Japan midfielder Keisuke Honda hit the crossbar on his debut and Riccardo Montolivo pulled one goal back, but they could not force an equaliser.
- Sports & Recreation
- Christian Abbiati
- Mario Balotelli