Inter Milan defender Stefan de Vrij admits defeat to Sassuolo was not good enough on the weekend.

Domenico Berardi earned the winner for Sassuolo from the spot.

“They prepared for the game like this: they were waiting for us to come out," De Vrij told Rai Sport.

“We made too many mistakes in the first half, opening ourselves to too many counterattacks.

“We must work hard and do better in our next game. There's still so much to work on."