Samantha Perelman has won a key victory in the brutal court battle for her grandfather Robert Cohen’s $600 million estate after a judge ruled there was “evidence of suspicious circumstances” which may have led to her being cheated out of her inheritance.

The 23-year-old daughter of billionaire Ron Perelman and late New York Post gossip queen Claudia Cohen is suing her maternal uncle, Hudson News mogul Jimmy Cohen.

She claims he manipulated her grandfather, the patriarch of Hudson News, into altering his will and leaving her out of it before he died in 2012.

Up until now the burden of proof had been on Samantha. But that changed Monday morning when Bergen County Judge Estela De La Cruz shifted the burden to uncle Jimmy’s team, citing his close relationship with Robert Cohen.

“This court finds that Samantha Perelman has presented evidence of a confidential relationship between Robert Cohen and James Cohen,” De La Cruz said, adding the “evidence presented of suspicious circumstances” includes James taking a 2007 solo trip to meet with one of Robert’s estate planners, an insurance broker, at his offices on Long Island.

The judge said there was enough evidence under New Jersey law to entitle Samantha “to a presumption of undue influence [used by Jimmy]. And the burden hereby is shifted to James Cohen to rebut the presumption of undue influence.”

The ruling means Jimmy has to give a more robust defense. But his spokesperson told The Post, “This procedural ruling in no way affects our confidence that we will once again demonstrate Robert Cohen always intended for his son James to inherit the business he helped build.”

Samantha earlier told the court that she understood from her mother, who died of cancer in 2007, that Jimmy was to get the family business after Robert died — but that she would inherit her mother’s cash share of the fortune. The trial is ongoing. Cohen is presenting his defense but has yet to take the stand.