Lisa Budd, a former secretary, will claim at the London North industrial tribunal that Mr Duff in effect dismissed her for daring to trespass on exclusively male territory as a master of ceremonies.
Miss Budd, 29, was sacked after becoming the first woman MC at a boxing match last year. She will tell the tribunal that she had a passion for boxing when she became a secretary in 1990 at the Anglo-American Sporting Club, owned by Mr Duff.
Last year she decided to fulfil her ambition to appear as an MC and was awarded a licence from the British Boxing Board of Control. Miss Budd claims Mr Duff expressed his disapproval of her plans saying that it was not a 'woman's job'.
Lawyers for the Equal Opportunities Commission will argue that when she appeared as the first female MC on 17 September last year it was with his full consent.
Miss Budd claims that Mr Duff was angered by the media attention and told her to choose between her job and her desire to act as an MC.
Mr Duff was unavailable for comment last night, but it is understood he will say Miss Budd was dismissed over her job performance.