Pep Guardiola has said the Premier League title race will be "over" if his Manchester City side drop points at West Ham on Saturday.
City visit the relegation-threatened Hammers a few hours after Arsenal's home game with Everton, live on Your Site.
The Gunners can move 10 points clear for a few hours at least if they beat David Moyes' side and Guardiola said his team, who lost 3-0 to Real Madrid in the Champions League in midweek, have no room for error.
"Now it's West Ham that defines the Premier League," said Guardiola. "The league is the most difficult title. I believe it's the most difficult one.
"Now we go there knowing that if we drop points, it will be over."
City dropped points last time out in the Premier League courtesy of a 2-2 draw at home to Nottingham Forest, who are battling West Ham to avoid relegation this season.
"I've always said when we arrive in the last 10 games every team plays for something," said Guardiola. "For relegation, for Europa League, for Conference League, for Champions League, to be champions.
"It's a pleasure to be here. Last season we could not be here [fighting for the title].
"It's normal, every game. Now there are no second chances."
On bouncing back from a disappointing defeat to Real in the first leg of their last-16 tie on Wednesday, Guardiola added: "Tomorrow night, we have a game, an important one for the Premier League position.
"Then we have the second leg,"
The defeat to Real led to the City boss receiving criticism for the attacking line-up and tactics used at the Bernabeu, which have now given his side a mountain to climb when they meet at the Etihad on Tuesday.
"How many times do I say Pep is a genius?" said Guardiola in his pre-match press conference when asked about team selection.
"I said to you after the press conference in Madrid, there are logical reasons for that [team selection]. The momentum of the players and many things.
"Listen, I played a final in the Champions League without Fernandinho as a holding midfielder against Chelsea. Do you think that's normal? No, honestly. I played (Ilkay) Gundogan at that moment.
"I was destroyed. They were right, but in that moment, I knew how he's playing and Fernandinho was playing.
"I can explain that to you, but is that going to convince you for the next time? If you win, you're a genius. How many times have I said 'Pep is a genius for the team selection?' I don't waste my time.
"My players are extraordinary, and they were extraordinary in many things. You can say whatever you want. I will convince you, when the selection is made. I want to rotate the team; we want to be good.
"After 10 years, I will not convince any one of you. Why? Because we lost. And that's all. I had to do my job the best I could, knowing that if we win, it's good. So, if we lose, it's bad."
