Shkodran Mustafi has apologised to Valencia supporters after his side suffered a heavy 7-0 defeat to Barcelona at Camp Nou on Wednesday.
Luis Suarez scored four goals and Lionel Messi netted a hat-trick as Barca gained the advantage in the first leg of their Copa del Rey semi-final.
Mustafi was sent off just before half-time with Barca already leading 3-0, and the Germany international apologised to the club's fans and staff for the poor display.
"We want to say sorry to the supporters and to the people who are working for the club," he told reporters.
"But you can't ask for forgiveness without reaction. It's not the time to talk about other sides.
"We have to lift ourselves up and that is not easy. In the coming days we have to front everything like men."
Mustafi said he could not blame himself or anyone for the loss, but instead rallied his team-mates to stick together.
"I do not look at who made the errors. In the good and bad moments we are together as one," he added.
"The dressing room is the one in s**t at the moment.
"But I believe in this team, and that is why I signed for this club. We were a team last year, and we are this year.
"For many people this has been the worst game of their career.
"We need to lift our heads like men and grow. The dressing room has to lift. The return leg is not to overcome the score, but to ask for forgiveness."