John Barnes says Manchester United are placing too much focus on their attack in the transfer market.
United continue to chase Jadon Sancho - or an alternative to the Borussia Dortmund attacker - with time running out in the summer transfer window.
Yet Barnes believes the Reds need to change tack and rival Manchester City for Kalidou Koulibaly in defence.
"Manchester United should look to sign a player like Kalidou Koulibaly, he has all the trademarks of a player they need in the heart of defence," Barnes told BonusCodeBets.
"As well as that, they should sign definitely sign a defensive midfielder as they look rather weak back there.
"Everyone talks about Jadon Sancho playing with Marcus Rashford and Bruno Fernandes if they were to bring him in, but there is no good being joyful about these options, if they can’t defend or have hardworking defensive midfield players to support them when they don’t have the ball.
"Manchester United have always been about having the best attacking players in the world, but you can’t do that until you have the right balance, and currently they don’t have the right balance at all."
He added: "Manchester United have a good squad with some decent players but the problem Ole Gunnar Solskjaer has is that his players like to get carried away if they play well and win a game, the next week they take their eye off the prize and performance drops.
"One week Marcus Rashford and Paul Pogba play well but the next week they don't.
"United just don't seem to have much consistency."
