Former Manchester United defender Gary Neville believes Manchester City should be "walking" their way to the Premier League title.
City were deposed as league leaders by Leicester City after slumping to a 4-1 home defeat to Liverpool on Saturday.
Manuel Pellegrini's men remain favourites to win the Premier League for a third time in their history, but Neville - who lifted the trophy eight times with United - has been disappointed with their performances in the first half of the season.
He said on Sky Sports: "Manchester City should be walking this league and that's not being disrespectful to them. The players and squad they have and quality they can show, they really are under-performing to be where they are.
"I still think they will win the league, but they are under-performing and they are under-selling themselves."
Ex-Liverpool centre-back Jamie Carragher echoed those sentiments, saying: "The one worry would be is that they've lost 4-1 twice now, to Tottenham and Liverpool - two teams you would say are very similar, they rely on high energy.
"If you think of City at their worst there is a sort of lethargy in their play, we've spoken about [Kevin] De Bruyne and [Raheem] Sterling and adding that energy, but there are still those players who have been criticised over the past few years for lacking that energy.
"And you think, will other teams look at that and think: 'Is that the way to beat Manchester City?'.
"For the quality that they have, they should be at the top of the league. I still think we all believe that they will win the league. But you've always got a doubt with City.
"I think Alex Ferguson mentioned a few months ago that even when they won the league they've won it sort of last day, or on goal difference, not really blitzed anyone out of the way. And that's what you believe they should do with the squad they have."