Nathan Ake out of Manchester City’s FA Cup semi-final against Sheffield United

The in-form Netherlands international was forced off in the second half of City’s Champions League quarter-final clash at Bayern Munich on Wednesday.

The club are still to learn the full extent of the problem but the 28-year-old is at least facing a short-term absence.

Guardiola, whose side face a crucial top-of-the-table Premier League encounter against Arsenal next Wednesday, said at a press conference on Friday: “He’s not ready for tomorrow but I don’t know the damage. Today, they make the final test to know exactly what he has.”

Phil Foden rejoined the squad in midweek after a lay-off following an appendix operation but was an unused substitute as City secured a Champions League semi-final place at the Allianz Arena.

“He was on the bench after two training sessions,” said Guardiola. “Every day that passes he will be better.”

Guardiola will assess his squad after their exertions in Germany – where City claimed a 1-1 draw to progress 4-1 on aggregate – before considering changes for the Blades clash at Wembley.

He said: “I have to see the players and how they feel.

“After the game in Munich they couldn’t really celebrate in the locker room because of how exhausted they were but I’ve rotated a lot in previous seasons and it wasn’t good.

“I have to think about it. I have many doubts about the line-up.

“I have to see the training sessions and talk with many of them and see what is my feeling.

“Of course they are going to say they want to play but we have to be sure that the people are in the (right) condition.”

The Blades, who are second in the Sky Bet Championship and closing in on promotion, have their own selection issues with two of their key players – City loanees Tommy Doyle and James McAtee – ineligible.

Unlike Munich in midweek when City did come up against another of their own players in Joao Cancelo, domestic competition rules prevent players out on loan facing their parent clubs.

Guardiola feels that is a shame for the tie and for the players.

He said: “The Championship is a good test to prove yourself. We’re incredibly delighted for them.

“Unfortunately they cannot play. We would’ve loved that. We loan players to get experience and what better experience would there be than to play a Premier League team in the FA Cup semi-finals for their development? Unfortunately the rule is the rule and they cannot play.”

Guardiola, who has lost four of his previous five FA Cup semi-finals, is expecting a tough test from the Yorkshire side.

He said: “They are one or two games away from being promoted to the Premier League. That’s already done.

“It will be an extremely difficult game for the quality they have. They are really good at set-pieces, really good in the build-up and linking in the channels. They’re so aggressive in the duels.

“We have to be there, absolutely, to deserve to be in the final.”