The England international was substituted at half-time during Manchester City's Champions League clash with RB Leipzig.
Foden was back in the squad after a lengthy spell on the sidelines against Aston Villa last week and made his full return to the starting line-up in a 3-1 win over Watford on Saturday evening.
He's Pep Guardiola's first choice on the left-wing, but is usually shuffled along the front three to cause problems across different parts of the opposition's defence.
City had missed Foden's impetuous during his spell on the sidelines so would have been worried about his early substitution on Tuesday evening.
Pep Guardiola told the press post-match, "Phil (Foden) had problems in the beginning with his ankle, as a precaution I decided to play Raheem (Sterling) in his position."
However, early indications from the Daily Mail suggest the injury may not be as bad as first feared.
Foden damaged his ankle just days before England's Euro 2020 final with Italy and it's a problem that's re-occurred at various points in the past six months.
At 21-years-old, the youngster has plenty of time on his side, but he'll want to shake off his ankle concerns as quickly as possible and hope it doesn't turn into a long-term issue.
Some Manchester City fans have reacted to the concerns over on City Xtra's Twitter page, with many noting that Pep Guardiola selecting Foden for a game of limited importance is very disappointing.
Here are a few of our favourites:
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