Boxing manager Barry McGuigan defended top stars being charged thousands of pounds for tickets to Carl Frampton's world title contests.
The High Court was told golfer Rory McIlroy and Snow Patrol singer Gary Lightbody were among those who paid for seats at shows in the United States.
Mr McGuigan said: "On big fights like this, you don't expect to give tickets away whether they are a celebrity or not."
Details of the high-profile payments emerged on day 11 of his multi-million pound courtroom showdown with Mr Frampton.
The Belfast fighter is suing his ex-manager for alleged withheld earnings.
Mr Frampton has made claims against Cyclone Promotions UK Ltd - of which Mr McGuigan was a director - over purse fees, broadcasting rights, ticket sales and merchandising.
In a counter lawsuit, the former two-weight world champion is accused of breaching his contact when he split from the company in 2017.
Both men deny the respective allegations against him.
Under cross-examination, Mr McGuigan was pressed on tickets sold for the boxer's two world title bouts against Leo Santa Cruz.
The court heard Mr McIlroy paid £1,280 into a Cyclone Promotions account for tickets for the first fight in New York in July 2016.
"He sat close to me," Mr McGuigan confirmed.
"It could be that he bought tickets for his colleagues, he had a couple of people with him, so that could have been for them.
"I would imagine Rory would have got a seat anywhere in the world for free."
But Gavin Millar QC, for Mr Frampton put to him: "Nobody discussed with Mr Frampton charging Rory McIlroy for a ticket, did they?"
Mr McGuigan insisted, however: "It doesn't say there that it's for Rory. He's paid for it, it doesn't mean that it's necessarily for him, it could be for his colleagues, it could be for his security guard."
Tickets bought for the rematch with Santa Cruz in Las Vegas in January 2017 also came under scrutiny.
Mr Lightbody, frontman in the rock band Snow Patrol, paid £2,000, the court heard, while television and radio presenter Colin Murray paid £750.
"Again, nobody spoke to Mr Frampton about these people being charged for tickets for his fights, did they?" counsel asked.
Mr McGuigan told him: "You go along to watch him fight, you expect them to pay for their tickets. That's the business, it has to work that way otherwise why not let everybody in for free."
He said he was sure that all of the money had been accounted for and put through the accounts.
"It was all straight and above board," he added.
"On the celebrity side of things, sometimes celebrities pay for tickets, sometimes they don't," Mr McGuigan explained.
"Sometimes they bring colleagues with them, sometimes they pay thousands of pounds for those colleagues to come with them.
"If we were to give away tickets to everybody the whole show would be a disaster, that's just the way it works."
The court also heard a Cyclone Promotions company account was allegedly used to pay restaurants, a clothes shop, antiques store and a furniture shop.
Bills paid through it were said to include:
Submitting that the payments had nothing to do with promoting Mr Frampton's career, the barrister said: "These are McGuigan family personal expenses being paid out of this account, aren't they?"
Mr McGuigan replied: "It appears so, yes."
He maintained, however, that he had no knowledge of the specific spending alleged.
In his case Mr Frampton claims he was promised a 30% share of profits to go into partnership with his ex-manager in another Northern Ireland-based Cyclone Promotions company.
But Mr McGuigan categorically rejected the allegations.
"That's a joke. That's just nonsense," he said.
"The amount of money that we paid him, how could we possibly have been able to pay him 30%, that's nonsense, absolutely nonsense."
During his evidence he stressed repeatedly that his focus was always on looking after his fighters, leaving others to deal with the financial side of the business.
However, Mr Millar claimed: "The idea was for this company to be a vehicle for McGuigan family members to earn money for themselves from the efforts of my client in the ring.
"That's why all those other family members were made directors of this company."
Mr McGuigan replied: "That's untrue, he got paid more than anybody else was willing to pay him, and handled perfectly and managed excellently to win him three world titles at different weight divisions. I don't know how I could have done a better job."
Asked why his wife Sandra, and sons Jake, Blane and Shane were made directors in the company, he said: "Because they worked their cotton socks off to make that young man a success.
"They worked exceptionally hard; long days, day after day after day, months after months to get him to where he had to be, I believed he could be, and I was right."
The case continues.