Manchester United face a battle to reach the Europa League quarter-finals after being stunned 3-2 by Athletic Bilbao in the first leg of their last-16 tie at Old Trafford on Thursday. United took a 22nd-minute lead through Wayne Rooney but Bilbao roared back with goals from Fernando Llorente, Oscar de Marcos and Iker Muniain before Rooney reduced the damage ahead of next week\'s second leg with an injury-time penalty.