Marcelo has confessed that a change of mindset is required at Real Madrid, but has declared himself happy with the club's current squad.
The reigning European champions suffered their first loss in an international final as they came unstuck against domestic and city rivals Atletico Madrid in the UEFA Super Cup.
A Cristiano Ronaldo-less Madrid lost 4-2 in Ernesto Valverde's first competitive match at the helm, with the early setback raising questions over the quality of Los Blancos' squad heading for the new season.
Marcelo has no complaints on that front, however, telling reporters in Tallinn: "You have to focus on what we did well today. I feel that we put in a good shift. We had the ball, played as a team, and we fought as best we could.
"We need to change our mindset because we have a whole season ahead of us. I don't make the signings. The squad looks good to me. We are united as a group. We played a good game until extra time.
"The winners are those who make fewer mistakes. Tonight, we failed and we don't want to make those errors again because it cost us a final.
"They made fewer mistakes and deserved to win it. These are mistakes resulting from fatigue, from not much training. Many players have been late back due to the World Cup, but that is no excuse."
Real Madrid conceded four or more goals in a game for the first time since November 2015, having never done so during Zinedine Zidane's tenure.