The 28-year-old fashion designer - who won the fourth season of reality show 'Project Runway' in 2007 and debuted his first collection at New York Fashion Week in 2008 - clashed with the 'Tammy' star when he was asked to design a gown for her to wear for the 2012 Academy Awards because they couldn't agree on a style to suit her curves.
He told the New York Daily News: ''Quite frankly she was quite difficult to work with. She wanted some specific things that I thought would not look good on her body.
''And she was not comfortable with them in the end.''
Christian's revelation comes just weeks after the 43-year-old actress claimed that multiple designers had refused to create a dress for her for the very same ceremony - at which she was nominated in the Best Supporting Actress category for her role in 'Bridesmaids'.
She told Redbook magazine: ''Two Oscars ago, I couldn't find anybody to do a dress for me. I asked five or six designers-very high-level ones who make lots of dresses for people-and they all said no.''
Meanwhile, Melissa is set to launch her own clothing line 'Pearl' after alluding to the possibility of starting up a plus-size range in June.
She said: ''When I go shopping, most of the time I'm disappointed.''
The mother of two - who briefly studied fashion and textiles at Southern Illinois University - teamed up with her friend Daniella Pearl to create the collection after the pair worked together to create her 2011 Emmy Awards gown.
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