Hall has appealed to the Toon Army to lay off owner Mike Ashley and his under-fire manager - for the time being at least.
"It's vital the fans get behind the team for what is a must-win game," Sir John, who sold his 42 per cent stake in Newcastle to Mike Ashley seven years ago, told the Daily Star.
"Of course, I understand their grievances but the Leicester game is neither the time nor the place to air them.
"That would be seriously counter-productive and play into the hands of the opposition.
"Players can sense when the mood's not right in the stands and in our position, they can't afford to be distracted.
"The side Alan Pardew sends out has to be in the right frame of mind and they won't be if they think it's going to turn ugly."
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