KARL Robinson is calling on former England boss Sam Allardyce to help work with Charlton’s defence.

Robinson was on the back-room staff when Allardyce managed Blackburn and the pair have remained close.

Allardyce was in the directors’ box at the Valley for last week’s win over Doncaster and the Charlton chief hopes he will agree to put on a clinic for the back four.

Robinson said: “He’s someone who has done so much for me since I was a young boy coaching in the Premier League. He is one of the best managers and coaches in the Premier League.

“He’s hopefully going to try and do something with the back four for me.

“He has been here three or four times and I haven’t lost. If he wants a first-team coaching job, I’m sure we would give him a desk!”

Charlton were one of the most impressive sides to face the Bantams last season but their campaign never got going amid on-going political strife between the owners and fans.

But they are tipped to be firmly in the mix this time and currently sit three points behind City in fifth, with a game in hand.

They drew 1-1 at Oxford on Tuesday and recently won 3-1 at Fleetwood.

They are likely to head north without Mark Marshall after City’s reigning player of the year suffered a thigh strain.

The winger has only just returned from knee ligament damage he suffered in a pre-season friendly in July. He made his comeback off the bench against Fleetwood.

But Marshall has sat out the last two games and Robinson is not optimistic about him being ready in time for his former team.

Robinson said: “It is a little bit worse than we thought. He did something quite unusual from a biomechanical perspective and that’s where he felt the twinge.

“He stopped right away and got immediate treatment on it. (But) It won’t be a massive one in terms of timescale out.”