Manchester United captain Roy Keane has warned his defence they could not hope to recover the 3-0 deficit in the Champions League that they allowed Spurs last Saturday.
"You wouldn't want to put yourself in a position like that in the Champions League. It may be great to watch but try that against some of the top teams in Europe and you will come unstuck.
"You cannot go 3-0 down in the Champions League and expect to get anything out of it.
"We should know, because we were 2-0 adrift against Bayern Munich last season and could not salvage it, and 3-0 behind to Real Madrid and on our way out the season before," Keane said.
"The foundation for any good team has to be keeping clean sheets. But you attack as a team and defend in the same way. It is a shared responsibility and we gave the ball away far too easily against Deportivo last week," he said.
"It is up to the existing players to pick up their performance level and work even harder than before to keep pace with the demands on us," Keane said.
"Because results have not been brilliant so far, it is easy to single out the new boys for criticism. But that would be wrong. They have come in and been great.
"I am happier than I was but still not completely happy that we are playing as we should be. There is no doubt that we still have a lot of work to do before we get up to the standard people expect of us".