Norwich City striker Ashley Barnes has undergone calf surgery that looks set to rule him out of the Championship kick-off.

The 34-year-old was pictured in recent days on crutches attending a social event with some former Burnley team mates, after missing the club’s trip to Belgium last week and the opening friendly at Northampton.

New City head coach Johannes Hoff Thorup indicated Barnes was still troubled by the injury that had limited his impact at the end of the last campaign, and had not been involved so far in pre-season team training.

The usual recovery time for a calf operation can be between six to eight weeks, with City set to begin their Championship season at Oxford on August 10.

Barnes lasted 15 minutes of a home league game to Swansea on April 27, after his late introduction from the bench.

Former boss David Wagner confirmed a calf injury after subsequent scans, but City’s medical staff were able to get him back on the pitch for 81 minutes of the play-off semi-final, second leg capitulation at Leeds in early May.

But the decision was taken for the experienced frontman to go under the knife this summer. Barnes also missed six weeks of last season before Christmas, when he suffered a knee injury against Leicester.

The forward provided 11 goal contributions in 35 Championship appearances during his debut season for Norwich, after signing a two year deal as a free agent following his departure from the Clarets, but Thorup has not had a chance to assess the striker on the pitch.

“Barnesy had that injury from the end of the season and he's not really fit yet. And we've kept him out of training,” said the Dane. “So we have to assess him and wait and see what we will do with him but it will take some time from what I see.

“It is the same injury that he keeps on struggling with, so we really have to see what we can do to make him ready as fast as possible. But I think it will take a little time.”

Thorup has Adam Idah and Josh Sargent as his frontline options, although both have been linked with moves away in this transfer window.

Youngster Ken Aboh pledged his future to the club by signing a new deal earlier this summer. The 19-year-old striker scored at Sixfields, and was on target for the Under-21s at Wroxham on Tuesday night.