The disgraced Newcastle United star tried to pay off former team-mate Jamie Tandy for the attack which could have blinded him.
But Jamie, who claims it wrecked his football career, has rejected the out-of-court compensation settlement.
His legal advisers believe he could get THREE TIMES as much.
Last night one said: "Jamie was a talented footballer with a bright future ahead of him so we believe there is a strong case for a minimum of £300,000.
"Even that figure is fairly modest given the vast sums of money Premiership footballers earn."
Jamie, 24, and Barton were both playing for Manchester City when the incident happened at the team's Christmas party in 2004.
Jamie's career nosedived and he now works as a window cleaner.
He suffered a string of personal problems, receiving help for a booze addiction and a failed suicide bid.
Lawyers acting for midfielder Barton, 27, have made Jamie two recent compo cash offers but both have been turned down.
Our source said: "The latest one was in the region of £100,000 but that was judged to be well short of the figure we are seeking."
A compensation hearing is now scheduled to take place at the High Court in Manchester in November.
Liverpool-born Barton, who earns £60,000 a week at Newcastle, is desperate to avoid another damaging court case.
He has previously served six months in jail for a separate assault in a Liverpool McDonald's.
And he got a four-month suspended sentence for attacking another City team-mate Ousmane Dabo.
Jamie is trying to rebuild his career and has signed with non-league football site Witton Albion.
Our source added: "It's now going all the way. Barton's people will have to make a significant improvement for things to resolve before court."
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