Fit: Erling Haaland
Haaland has struggled in front of goal of late, and went into Tuesday night's Champions League last-16 second-leg clash against Real Madrid with just four goals in his last 17 appearances.
But he was extremely lively at the Etihad Stadium as City chased down an unlikely comeback against the Spanish giants, recording five shots on target including an equalising goal on the night.
However, with City needing three goals to force extra time, Haaland was replaced by Omar Marmoush with more than 30 minutes of the match to play.
Haaland was seen afterwards shaking his head while sat on the substitutes bench, watching on as City failed to add to their tally before Vinicius Jnr scored his second of the night to send City crashing out with a 5-1 aggregate scoreline.
City are next in action on Sunday at Wembley with the first silverware of the season up for grabs, and Guardiola was asked if Haaland's withdrawal was down to any injury concern.
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"Erling Haaland has no injury," Guardiola told reporters. "He will be available against Arsenal in the Cup final."
Speaking on Amazon Prime Sport, former Manchester United striker Wayne Rooney disagreed with Guardiola's decision to substitute Haaland.
"I would like to have seen him stay on longer and for City to try and score the second goal," the player-turned-pundit said.
"Pep and Haaland knew the tie was over so they chose to rest him."