How will the back four cope?
The relocation of Luke Shaw and recall of Tyrell Malacia at Leeds indicated both will start at Camp Nou. Erik ten Hag swears by a right-footed and left-footed central defensive partnership and Shaw has fared favourably on the four occasions he has moved inside this season.
Yet he is likely to encounter the most prolific No.9 on the planet in Robert Lewandowski. Shaw should at least have the benefit of Raphael Varane alongside him. Varane has played against Lewandowski when he was at Borussia Dortmund and Bayern Munich, as well as at the World Cup in December.
