Manchester City lost the Premier League title when opting not to sign another centre-half over the summer, says Richard Dunne, with Pep Guardiola urged to consider a move for Leicester star Jonny Evans in the January transfer window.
The Blues have dominated the domestic scene in recent years, claiming back-to-back crowns and an historic treble in 2018-19.
They have, however, suffered the odd wobble this season and are currently 17 points adrift of leaders Liverpool.
Defensive leaks have proved to be a problem, with injuries hitting hard, and Dunne has questioned why those issues – with Vincent Kompany having departed – were not addressed when the opportunity presented itself.
The former City skipper told the Irish Independent: “If, as expected, Manchester City do end up losing their league title, they will really have lost it last summer in the transfer market when Pep Guardiola decided not to sign a centre-back.
“You need to plan for injuries and suspensions and City didn't do that. They seemed to think they would be OK, but they didn't take into account that injury to Aymeric Laporte or the form of Nicolas Otamendi.
“So they were wrong to not sign a defender in the summer. They did sign Rodri to give Fernandinho the chance to go and play in defence if he was needed, but they miss him in central midfield. More than anything else, that's their biggest problem.
“Otamendi and John Stones have never been rock solid but when they had Fernandinho in front of them, he stopped a lot of the threats before they got through and that Fernandinho-type player is not there as Rodri is not in the same vein, that's where they are losing the battle at the moment.
“City either need to sign a centre-back or get Laporte back, because for every two good games they have they will then have a slip-up. They just have that hint of instability about them, which they didn't have last season, and other teams in the Premier League can sense it.”
Dunne, who feels that problems at the back could also cost City in the Champions League, believes Guardiola should be looking to bolster his ranks in the New Year – despite claims that no money will be spent – with there value to be found in a Premier League market.
He added: “For all their attacking prowess, and it is very good, City have failed over the last couple of years because you always think they're not strong enough at the back.
“And now they need two centre-backs. One, Laporte, is out with an injury and the other two don't seem capable of putting together a string of performances to allow them keep clean sheets.
“I can't see Guardiola going out to buy one, but they need someone who could come in right now and help out. Jonny Evans has been brilliant for Leicester, he knows the league and I wouldn't be surprised if they did earmark him to come in for a year or 18 months.
“They will have to spend over £100 million to get a top-class centre-back, someone like Evans could be good in the medium term but he is doing well at Leicester, they are happy with him and he's happy there, so the Foxes would be entitled to ask for a very big fee.
“Toby Alderweireld is out of contract with Spurs at the end of the season, but would City really hand him a five-year deal?”