straight to your inboxGary Neville believes the battle for the No.1 spot at Manchester United between David de Gea and Dean Henderson has got 'a problem written all over it'.Henderson is back at Old Trafford after two impressive loan spells with Sheffield United and signed a long-term contract last month to signal his intent to become Ole Gunnar Solskjaer's first-choice goalkeeper.De Gea's form was patchy towards the end of the season and that has led to calls from some fans for Henderson to