Rafael Benitez was not fully convinced by his Chelsea players despite their 3-1 FIFA Club World Cup semi-final win over Monterrey in Yokohama on Thursday.
Despite the relative ease of the scoreline, Benitez feels his Blues side were quite slack in their play and has urged them to buck up before Sunday's final against South American champs Corinthians.
"I'm not very happy with the goal we conceded," he said.
"We won, which is fine, but still these little things can make a difference in a final, for example.
"When I talk about a winning mentality, always I talk about little details making the difference.
"The team has to think about winning, winning in style and not conceding because the goalkeeper (Petr Cech) likes clean sheets.
"They have to keep their concentration right to the end of the 90 minutes. That's what they need to do."