Simone Inzaghi was left "very angry" with Inter's approach in their 2-0 defeat against Sassuolo and warned his side to buck up their ideas if they want to retain the Serie A title.
Early goals from Giacomo Raspadori and Gianluca Scamacca made it a third straight league game without a win for the Nerazzurri, who also lost the first leg of their Champions League last-16 tie to Liverpool in midweek.
Inter consequently failed to reach the summit of the table despite leaders Milan being held by Salernitana on Saturday, though only three points separate the top three in the table. Inter sit two points adrift of Milan, with Napoli in third.
Sassuolo have now clocked up away wins against both Milan sides and Juventus this term, with head coach Inzaghi left frustrated by his team's poor application.
"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," Inzaghi said.
"We tried to do everything in the second half, created so many chances and were unlucky, but the fact remains we should have 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."
Lautaro Martinez drew a blank for a seventh straight game, while Opta data shows that since the resumption of the league after the mid-season break Inter have recorded 100 shots (36 on target) but managed only six goals.
They remain the top scorers in Serie A, though, and Inzaghi is sure his side will soon start finding the net with more regularity.
"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," Inzaghi added.
"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."
Matteo Darmian and Roberto Gagliardini were hauled off at half-time for Denzel Dumfries and Edin Dzeko, and Inzaghi would have liked to have made more alterations.
"I would have happily changed more than two at half-time," he said. "We lost some of our organisation, we tried to open it up again, but we have to analyse what went wrong today.
"There's another match in [five] days [against Genoa], we know that we play continually and need to be stronger than absences, bans, injuries, setbacks, everything.
"We're all in there and will see what happens at the end of the season."