The 35-year-old actress has left furious when her fellow Oscar-nominee Jennifer won at the Screen Actors Guild Awards, reported Showbispy.
"Jessica can't stand the fact that Jennifer is stealing her thunder! What is more, the critics have been gushing over Jennifer's awards show speeches and it has been killing Jessica," a source said.
"It was a real blow to Jessica when Jennifer took the SAG Award. Not only did Jessica think she deserved it, she thought she had it in the bag. She tried to put on a brave face for the cameras, but inside she was seething," it added.
And Chastain's ire went into overdrive when her nemesis joked about her during her recent Saturday Night Live gig.
"Jessica Chastain - more like Jessica Chast-ain't winning no Oscar on my watch. 'In Zero Dark Thirty' you caught Bin Laden. So what? In Winter's Bone I caught a squirrel - and then I ate it. Boom. Deal with that," Lawrence had said on the show.
"Jessica felt Jennifer trivialised her acting role and didn't see any humor in the bit. She can't stand Jennifer all the more for it," said the source.