Roy Keane still has his doubts about Manchester City as a top European club despite Pep Guardiola's side's blistering start the season.
City are currently five points clear at the top of the Premier League and already through to the Champions League knockout stages after seeing off Napoli on Wednesday.
The strong start certainly has former Manchester United captain Keane impressed with the way City are playing, but he's still not a believer that they can sustain their form.
"They're playing well. We obviously know trophies aren't given out at this time of year but, my goodness, they are playing some outstanding stuff," he said speaking to ITV. "They have momentum behind them.
"You just expect City to score three or four goals every game and they did it again tonight. Outstanding, and if they can keep that going they'll take some stopping.
"My only concern for City at the moment is that I think it is in their DNA as a club to mess things up," he added.
"They have previous where they've got carried away. But you look at their squad and the players they have if they get a bit of luck with injuries and the coach, and they'll take some stopping."
City host Arsenal on Sunday in their final Premier League match before the upcoming international break.