Marouane Fellaini says New Balance's boots are 'poor quality' and have caused 'considerable damage' to his feet.
The Belgian midfielder has a four year deal which he signed in 2012 with the sports company to wear their boots but wants to sue for damages after they walked away from a £600,000 a year contract.
He claims in a high court writ that the boots boots are "poor quality" and have caused "considerable damage" to his feet. The Belgian's representatives are also suing for "loss of enjoyment, inconvenience and impact on performance."
The 29-year-old also claims United's kit man has to steam and stretch the boots to help him put them on, according to the writ.
New Balance have replied to his claims, saying that the boots were "perfect" and that the Manchester United star asked for 12 more pairs.
After a difficult start to his United career under David Moyes and Louis van Gaal, Fellaini appears to have found his feet under Jose Mourinho having played a big part in helping them win two trophies last season and making a good start to the new season, despite Sunday's 1-0 defeat at Chelsea.