A TV presenter and doctor who is being sued by First Minister Arlene Foster for defamation was unaware the case had reached hearing, a court has heard.
On 23 December 2019, Dr Christian Jessen tweeted an allegation that Mrs Foster had been having an extra-marital affair.
The post remained online until Dr Jessen deleted it on 7 January 2020.
Dr Jessen claimed he had not received legal documents or trial dates for the libel action.
He has been ordered to travel to Belfast later this week to testify and face cross-examination by Mrs Foster's counsel, who has described his assertions as "beyond parody".
'Credibility under scrutiny'
The last-minute development is set to delay judgment on the level of payout to award the Democratic Unionist Party (DUP) leader.
The judge told Dr Jessen's barrister: "If he's saying that he didn't get any of that material and was only aware of the assessment of damages hearing in this case when friends contacted him to ascertain how he was, having regard to press coverage, if all that is being asserted as being true by your client then I'm afraid it is the case his credibility will be significantly under scrutiny.
"I see no other method in which that can be properly explored other than for him to give evidence live in this court in relation to these issues."
Last Wednesday, Mrs Foster told the court she was left humiliated by the unfounded rumour which "trashed" her 25-year marriage.
The first minister described it as "an attack on me personally and my marriage, meant to destabilise me at a very critical time".
At that time Mrs Foster was heavily involved in talks to restore power sharing in Northern Ireland.
"One of the things that gives me stability is my home relationship - it was almost as if this cut to the very core of my life," she said.
With no defence entered in the lawsuit, Mrs Foster has already secured judgment in default.
The judge had been due to rule on Wednesday on the amount of damages after hearing the first minister's testimony.
But Dr Jessen's lawyers lodged an urgent application for permission to make the case that he never received documents or dates for earlier stages in the proceedings.
Setting out his client's position, Gavin Millar QC said: "He didn't have notice in the sense of actual knowledge of either the entering of default judgment or the assessment of damages hearing."
Asked if his client had checked his accommodation in London for papers sent there, Mr Millar replied: "As far as I understand it he hasn't found a trial bundle in the apartment."
However, Mrs Foster's lawyer claimed there could be no doubt that all of the information is in Dr Jessen's London flat.
"If the court believes for one moment that this man for 12 months has lived elsewhere, not had a forwarding address and didn't tell his concierge service, all of (that) is beyond parody," he said.
Putting his judgment on hold, Mr Justice McAlinden adjourned until Friday when the defendant will attend court to give evidence in person.
He added: "I have to deal with this issue before delivering judgment in this case."