Sevilla coach Michel was disappointed with his side after they slumped to a surprise defeat against Celta Vigo on Friday.
Celta Vigo, who won promotion from Spain's second tier last season, stunned Sevilla with a 2-0 home win, which came thanks to second-half goals from Iago Aspas and Enrique de Lucas.
The loss was a blow to Sevilla, who have been in good form this season, with their win over Real Madrid a highlight of their campaign.
And Michel admitted his side were second-best, paying credit to the underdogs.
"It was not only a bad result but also the performance in this game was very bad," Michel said.
"We cannot deliver this performance, especially after the good performances we have been putting in. We played poorly tonight and I have no excuses.
"Celta Vigo are a good team, they are very quick when they attack and took full advantage of the chances they had.
"When the game was level at 0-0 they won the decisive penalty, in this moment the game has changed. Whenever we did have a chance, their goalkeeper Sergio (Alvarez) stopped it."