Pep Guardiola believes that his Manchester City side cannot afford many more slip-ups in the race for the Premier League title.
Last weekend's loss at Newcastle – City's fourth of the campaign – has left them seven points behind leaders Arsenal.
The Gunners have been in superb form so far this season, suffering just one defeat in 12 games.
"We cannot lose games, absolutely – that is the truth," City manager Guardiola said on Friday.
"They are so strong and winning games, and winning games in a way where they are so solid, like we had in the past with Liverpool against us and they were not going to drop many points.
"That's why you have to be up there and this is what we will try to do."
Reflecting on the Newcastle loss, he added: "We made a really good game, we created more in Newcastle than previous seasons and it was quite good, but we lost.
"Now we have to regain our momentum to start winning games and being there because there is still so long in the season."
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City endured another disappointing defeat when a team showing 10 changes to the starting line-up went down 2-0 to Bayer Leverkusen in the Champions League in midweek.
Guardiola felt his players were too risk-averse against the German side.
"We didn't try. In football when you play on the green you have to try things and we didn't try."
He added: "I think they played not to make mistakes, not to play to do something, that is so difficult. In football you have to play offensive and you have to try... they played to be safe."
Guardiola, whose team face struggling Leeds on Saturday, suggested that the players who started against Leverkusen had lacked confidence.
"I have a lot of confidence in them, still right now I have a lot," he said. "I have a huge value in what they are as football players, and that maybe is higher than (they have) themselves."
There were occasions against Leverkusen when City players tried to rally the crowd, but Guardiola said he could understand the supporters' lack of enthusiasm.
"As a fan I would not cheer my team, playing in the way we played. I don't blame (them), I blame myself. Our fans make the effort to come to see us and we are incredibly grateful, and I know the stadium because I've been here for many, many years.
"If you do what you have to do, they are there, and this is what you have to try to do."
City are still without midfielder Rodri for the Leeds game but Guardiola said the Spanish international would be back soon.