Joaquín Correa scored Sevilla's solitary goal at the Vicente Calderón after coming on as a substitute against Atlético Madrid.
After the match, he told club media: "The result is a bit misleading. A set piece disorientates you and after, in the second half, the second goal came at a time when we had the ball, but we've got to keep going.
"We've got to be strong and united as a group. Bad times occur in football and we have to be together."
Correa continued: "It is obvious that we have had a blip mentally in a few recent games, but it's time to show what we're made of and win our remaining games."
The Argentine said the team has to show "sacrifice and humility like we always did. It's a very hard time and we've had a bad week, but we have to be united and have humility and keep working."