Gordon went off just before the half-time break at the Etihad Stadium after going down clutching the back of his leg.

He was unable to continue after being assessed by Newcastle’s medical staff, with more detailed scans set to take place in the next 24 hours.

Gordon is already a major doubt for Saturday’s home game with Brentford and next Tuesday’s trip to Tottenham, with his participation in the forthcoming FA Cup tie against Aston Villa and two-legged Champions League game against Qarabag far from certain.

“It looks like a hamstring problem,” admitted Howe. “I don’t quite know how bad it is, but it as enough for him to come off, so that’s a big worry.”

Harvey Barnes replaced Gordon, with Howe making three further substitutions at half-time, with his side trailing 3-0 on the night.

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