Ed Sheeran's promoter is being sued by ticket reseller Viagogo for allegedly defrauding music fans.
Viagogo claims that Stuart Galbraith's firm, Kilimanjaro Live, set up fake Viagogo stalls during Mr Sheeran's 2017 tour where it voided genuine tickets and told fans to buy new ones.
Mr Galbraith described Viagogo's allegations as "totally false".
Viagogo's move is the latest in a long-running feud between artists and their promoters and ticket resellers.
Mr Sheeran himself has been vocal in criticising secondary ticketing sites for snapping up thousands of tickets only to resell them above their face value.
Swiss-based Viagogo filed the lawsuit against Mr Galbraith and Kilimanjaro Live a day before both companies are due to appear in front of the Department for Media, Culture and Sport select committee.
Christopher Miller, head of business development at Viagogo, will face questions from MPs, including about the firm's conduct.
Analysis: Simon Jack, business editor
This is the latest move in a long-running and bitter feud. Both sides accuse the other of ripping off fans.
The Competition and Markets Authority issued court proceedings last month against Viagogo, accusing the company of giving customers misleading information about the availability and popularity of tickets, thus pressuring fans into needlessly hasty purchases of expensive tickets. It also got into hot water with the Advertising Standards Authority for failing to publish the full price of tickets including booking fees and VAT - although the company has since satisfied those concerns.
The timing of the filing of this lawsuit looks tactical, given that Stuart Galbraith and other senior executives from the ticket reselling industry will be facing a committee of MPs on Wednesday.
Proceedings are at an early stage and the BBC has not seen the evidence on which Viagogo's allegations are based. But the latest allegations, that Stuart Galbraith's campaign against Viagogo involved unlawful and fraudulent behaviour, seem to have ensured that this nasty dispute just got a lot nastier.
Last week, the Competition and Markets Authority filed a lawsuit against Viagogo over concerns it is breaking consumer protection law.
The competition watchdog took action against the big four secondary ticket sites last November.
However, while StubHub, Get Me In and Seatwave promised to change their business model, Viagogo failed to make the changes required resulting in the High Court legal action.
At the time, Viagogo failed to respond to a request for comment about the lawsuit.
Mr Galbraith will also appear in front of the select committee alongside Ticketmaster UK's managing director Andrew Parsons and Wayne Grierson, UK managing director of StubHub.
Mr Galbraith issued a statement describing Viagogo's allegations as "ludicrous, laughable and most importantly, totally false".
He said his firm would "defend against this action vigorously and look forward to doing so in court".