Jurgen Klopp claimed Liverpool have work to do after their heavy defeat to under-fire champions Leicester City.
The Reds' top-four aspirations suffered a blow as the champions, just four days after Claudio Ranieri's sacking, ran out 3-1 winners on Monday Night Football.
Klopp admitted his side, who returned to action after a 14-day break, were taken aback by the Foxes' display, forcing the German to concede it looked like the Reds had failed to prepare for the game.
"It looked like we hadn't spoken about the strength of Leicester and that's a real problem," Klopp told Sky Sports.
"We have to work, obviously, and to try to do everything better next time.
"The performance from the first second was not good enough, and that's how you lose football games. There is no reason for this. I'm not ready to look for an excuse."
Leicester's industrious display from the first minute provided some response to the criticism directed towards the squad, now under the tutelage of interim boss Craig Shakespeare, in the aftermath of Ranieri's axing.
Jamie Vardy's first Premier League goals since December 10 and Danny Drinkwater's stunning volley did the damage, Philippe Coutinho's second-half scant consolation for the Merseysiders.
"We never really got going tonight," Klopp added. "It's difficult to find the right words.
"There was not an over-aggressive game from Leicester, but even for this level we were not physical enough.
"They were ready, they had their set pieces and throw-ins ready and we gave throw-ins away like we hadn't spoken about them.
"It doesn't make sense to give Christian Fuchs 20-odd chances to throw the ball in. It's difficult to accept.
"They scored the first goal, that helped them a lot, then the second goal, where there was no protection to Drinkwater's volley.
"We could have defended better so it's very disappointing. It's difficult to explain in German but in English, it's worse.
"The manner of the defeat makes it worst. If we played our best game and lost, then I have to accept that because that is football."