Mr Hancock attempted to get the case thrown out, with his lawyers saying the claim did not have "a realistic prospect of success" and was not "properly articulated".
He previously said the case was "absurd" and labelled Mr Bridgen's claims "ridiculous".
But Mr Bridgen said he believed the comments intended to cause "grievous harm" to his reputation and were "seriously defamatory and untrue".
In a ruling last year, Mrs Justice Collins Rice found Mr Hancock's post was not "definitively condemning the MP as an individual" and that the majority of the publication was an "expression of opinion".
She added that she was "satisfied the ordinary reasonable reader would not have understood this tweet in the terms Mr Bridgen most fears".
But, in a judgment on Monday, she said "all relevant evidence" to determine whether or not Mr Hancock "genuinely espoused the opinion he expressed" in the post was not available.
She, therefore, decided to send the case to trial.
"Whether Mr Bridgen will ultimately succeed on his pleaded case in establishing the fact he alleges is likely to depend on a full examination of the evidence both ways, including how Mr Hancock explains his opinion in due course, if he chooses to do so, or the inferences to be drawn if he does not," she said.
"I am not in a position to conclude at this stage that Mr Bridgen's prospects of success on either matter are such as to be determinable now to be 'unreal'."