Inter Milan coach Simone Inzaghi says defeat to Sassuolo wasn't good enough.
Giacomo Raspadori and Gianluca Scamacca struck for Sassuolo in their 2-0 victory.
Inzaghi fumed: "I am very angry with the approach, because we had three days since Wednesday's game, we talked about the fact Sassuolo beat Juve and Milan away, they play great football and we had to be wary.
“We tried to do everything in the second half, created so many chances and were unlucky, but the fact remains we should've had a different approach. Sassuolo had great technical quality, they were fresher physically and it showed.
“We will analyse the situation, we know there are 13 games to go, we are all up there and want to keep going forward. The fact is, a team that wants to win the Scudetto cannot get the approach as wrong as we did today."
He added: "I don't think there is anxiety, the great champions are accustomed to these games. I think there was a lack of sharpness, there was some fatigue, both physical and mental. My staff and I tried to focus the players this week, but we conceded two early goals that we usually don't allow.
“We remain the most prolific side in Serie A this season and will get back to scoring goals soon. When you are a striker and don't score, you just have to stay calm, the goal will come."