Stoke City defender Robert Huth admits their defending hasn't been good enough recently.
Huth admitted no-one knows why their defence, which was one of the meanest in Europe going into the festive fixtures, has since conceded 13 goals in their past four top-flight games.
He said: "I can't put my finger on what's going wrong. We assess things after every game to stop mistakes but at the moment teams are cutting through us and scoring more than they used to.
"Hopefully we will get things sorted for next week because Manchester City are playing some good stuff."