Manchester United goalkeeper David de Gea has said the team's poor form is due to a "lack of quality" in certain areas.
United have won only two of their last eight Premier League games and sit ninth in the table, nine points behind the Champions League places ahead of Sunday's match at home to Aston Villa.
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"I don't think it's through any lack of effort, the boys are leaving everything out on the field in training and games," De Gea told Sky Sports.