Manchester United legend Peter Schmeichel has criticized Liverpool for their defensive instability this season.

The Reds' attacking quartet of Sadio Mane, Philippe Coutinho, Roberto Firmino and Mohamed Salah has been dubbed the 'fab four', and all four of them played together for the first time in the 1-1 Champions League draw with Spartak Moscow.

However, Schmeichel says that Klopp needs to stop thinking about 'fab four', and start worrying about his defensive four.

"It's so obvious what the problem is - we talk about the fab four, we should be talking about the flat four," Schmeichel told Sky Sports.

"The back four just doesn't work and the goalkeeper situation is very confusing.

"You can't win anything significant with an unbalanced team - you need to have equal quality up front and at the back."