Gary Neville claims Manchester United made a "real bad error" by not signing a right winger during the summer transfer window.
United fell to a 1-0 defeat to Arsenal on Sunday evening and struggled to create any chances of note during another lacklustre home performance.
Manager Ole Gunnar Solskjaer lined up his side in a 4-4-2 with a midfield diamond for the visit of the Gunners - the same shape that dominated RB Leipzig only days earlier.
But Neville believes United are sorely lacking the attacking-minded full-backs needed to play the system effectively, while they are also limited by the absence of a right winger.
"You have six midfield players at the club: Nemanja Matic, Fred, Scott McTominay, Bruno Fernandes, Donny Van de Beek and Paul Pogba and you’ve somehow got to get them into a system, which is forcing Ole to play a diamond," Neville told Sky Sports .
"I think there was an element of him thinking he could just put four players in that diamond and it would work after what happened in midweek but Scott McTominay on the right-hand side wasn’t working after five minutes.
Which formation is the best fit for Manchester United's players? Have your say here.
"You have to be comfortable moving out into that wide area. Aaron Wan-Bissaka’s already a bit awkward on the ball at right-back so you need someone to balance it and the balance on the right is a real problem for United.
"When Greenwood went off it was even worse. They wanted Jadon Sancho obviously to play on that side and it looks like a real bad error in not getting that position recruited.
"Changing systems, players, having plenty in one position and not enough in others is a real problem. Manchester United ’s full-backs aren’t the best attacking full-backs in the world.
"Luke Shaw’s okay going forward, he gives a bit of balance, but you’re playing a diamond and your width’s coming from players who don’t really play that position well in terms of being high and wide.
"It’s all looking a bit scruffy and towards the end, I’m not sure what shape United were playing. He might have to make some tough decisions, Ole."
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