A High Court judge might have to examine a series of WhatsApp messages if asked to rule on a row over footballer Marouane Fellaini's boots.
Manchester United's Belgian international midfielder says sportswear giant New Balance provided "defective quality" boots which had to be "steamed and stretched" by a United kit man before he could wear them.
An investment company which represents him has sued New Balance and wants around £2 million damages.
Rosalina Investments says "defective boots" had an "impact" on 30-year-old Fellaini's performance and caused a "loss of enjoyment" and "inconvenience".
But New Balance bosses dispute claims and say they provided "bespoke" replacements after Fellaini said he was "experiencing discomfort" when wearing certain boots.
Details of claims and counter claims have emerged in papers lodged by lawyers at the High Court in London.
Paperwork shows that evidence is contained in WhatsApp messages sent between Fellaini and New Balance staff.
Barrister Ruth den Besten, who represents Rosalina Investments, has outlined Fellaini's complaints.
"The football boots supplied by New Balance were of poor quality and caused considerable damage to Mr Fellaini's feet," she said.
"In order that the boots fit Mr Fellaini, they were required to be steamed and stretched by the Manchester United FC's assistant kit man."
She added: "Mr Fellaini repeatedly communicated his frustration with the poor quality of the boots."
But Ian Mill QC, who represents New Balance, said the sportswear firm had solved the problem.
"The player orally informed Mr Simon Crawford of New Balance that he was experiencing discomfort when wearing certain boots," said Mr Mill.
"New Balance therefore arranged for the player to be provided with bespoke replacement boots."
Papers include a series of WhatsApp messages containing Fellaini's complaints and replies from New Balance staff.
Lawyers for Rosalina said in August 2016 Fellaini had asked for boots which were wider and longer.
A month later he had sent a message saying: "a big problem no comfy at all."
At 2.10am on September 30 2016 he had written: "Hello my friend. I had a game tonight I played 90 min and after the game I can't walk my friend ... my toe one more than other but both boss I can't sleep... I have so much pain."
Later that morning he had added: "I have to see the pedicure this morning."
In November 2016 he said he had received "new ones" but they were "still the same. I have to stretch them".
Lawyers for Rosalina said in September a member of New Balance staff had replied: "We can fix it my friend ... we have the big dogs working on this."
The staff member had added: "Ouch... we are copying the nike boot for you... Your new ones arrive very soon, they will be like nike."
Mr Mill said in December 2016 Mr Robson had asked if new boots were "a good fit for you better than previous?" - and Fellaini had responded: "Yeah".
He said in January Mr Robson had asked: "Is the fit feel of the boots good?" - and Fellaini had replied: "Perfect for the boots."