Manchester United manager Jose Mourinho admits he is unsure what his best back four is after a tough start to the Premier League season.
Mourinho is under fire after United suffered a second loss in three league games with their 3-0 defeat to Tottenham at Old Trafford on Monday.
The Portuguese tactician is yet to start the same defence in any two games this campaign, with only left-back Luke Shaw starting all three matches and midfielder Ander Herrera used at centre-back against Spurs.
Asked if he knew what his best defence was, Mourinho accepted he was unsure.