Bacary Sagna believes Manchester City have been punished for complacency after slumping to their third consecutive defeat against Tottenham.
Kevin De Bruyne put City in front at White Hart Lane on Saturday before Spurs roared back to win 4-1 thanks to goals from Eric Dier, Toby Alderweireld, Harry Kane and Erik Lamela.
The result followed back-to-back 2-1 losses at the Etihad Stadium to Juventus in the Champions League and West Ham in the Premier League and Sagna has suggested City's impressive opening five victories may have left them feeling overconfident.
"Maybe we have shown too much confidence," he said. "I think we should have killed the game [against Spurs].
"We conceded that [Dier] goal just before half-time, but it's not the reason to come back sloppy in the second half.
"We had to keep some composure and we didn't have it. We were too nice, we lost too many duels and we have to be killers.
"Not just now, but against Juventus, we had the chance to score goals and we didn't. We lost the game. We have to learn, we have to keep positive."
City have now surrendered top spot in the table to Manchester United but Sagna has no doubt they will be challenging for the title come May.
"I think we have to keep working hard if we want to stay on top," added the former Arsenal defender.
"We know we have the quality players to make a difference, we know we can be champions."
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