Roberto Martinez admitted he was hurt by his side's 4-0 thumping at the hands of Liverpool in the Merseyside derby.
Liverpool recorded their biggest derby success since 1982 with a convincing victory at Anfield to move four points clear of their local rivals in the table.
Martinez conceded his sider were far from their best as he suffered his first defeat in a Merseyside derby showdown.
"It's a matter of admitting that we weren't at our best, but it's a day that hurts because it's a special day for our fans and we need to make sure we change this situation by playing how we have been between now and the end of the season," he said.
"It [the derby] means a lot and once we conceded the first goal maybe we got a little bit emotional with the game and we pushed so much forward to get that equaliser that we left ourselves a little bit exposed."
Martinez admitted they had let the game slip in the first half after conceding three goals before the break.
"It was a disappointing first half from our point of view. We had a period of around 15 minutes where we lost the game. We were desperate to come here and be ourselves and put in a performance where the fans could be extremely happy and proud.
"We started well enough but conceded the goal from a dead-ball situation and we put ourselves in Liverpool's hands really. We lost our concentration, lost our usual shape and it was unlike us."