Pep Guardiola believes physical tiredness had nothing to do with Manchester City’s Champions League defeat at home to Lyon on Wednesday.
City were beaten 2-1 by the French side, with Guardiola's side paying the price for a sluggish start by conceding two first-half goals before improving in the second period.
A number of his players were involved in the latter stages of the World Cup this summer, but Guardiola is convinced that had nothing to do with their lacklustre start at the Etihad in midweek, and remained hopeful they will improve when they face Hoffenheim on October 2.
"I don't believe in the physical condition [as an excuse] in my point of view," he said ahead of Saturday's trip to Cardiff back in the Premier League.
"I believe the mental condition controls everything you do on the pitch, what you do when you have the ball, what you do when you don't have the ball, how you defend set-pieces.
"They [the players] are young, they train every day and we take care of them.
"It is not like the Premier League, when you have another game, another game. Here, every game is like a final. There is a short group stage - one or two mistakes and you are out.
"But we still have five games [in the group stage] and we are going to prepare well when we go to Germany to make a good game."
Guardiola served a touchline ban against Lyon, leaving assistant Mikel Arteta to take control of the team pitch-side.
He does not believe that was a major factor in their defeat, however, and insisted his players had no need to apologise for the loss.
"The players don't have to apologise, apologise for what? They ran, they fought, they tried to come back but the opposition punished a lot of the mistakes we committed," he added.
"They don't need to apologise, they put everything in.
"I have to accept it [the touchline ban] and hopefully next game I can be there."