La Liga leaders Barcelona have slipped up in their chase of a second successive league title with a surprising loss at home against Real Betis on Sunday.
The European giants rallied back on more than one occasion but couldn't manage a single point from the encounter, losing 4-3 despite a brace from the returning Lionel Messi.
"We could not get back into the game at any time," Ernesto Valverde told reporters after the game, via Goal.
"We were not good in the first half and they got a positive advantage. We paid dearly for our first-half display.
"We did not start well and we are lacking something in general. We lack freshness when we have to finish attacks and we have to improve that.
"We knew that we were not going to dominate the match and it would be a case of 'give and take' although we thought we would end up with a better result.
"But to analyse my team I think we should have responded differently."
Valverde has also challenged Barcelona to improve if they want to win the Primera Division and the Champions League again, insisting there are several areas that need working on.
"We remain league leaders, but if we want to win La Liga and the Champions League, there are many things to improve," he remarked.
"The game started badly and they took advantage of the two opportunities they had. We were ready, but we cannot keep losing home points. Teams cannot come here and score four goals."