Manchester United midfielder Juan Mata had an influence on ref Mark Clattenburg quitting the Premier League.
The Daily Star says Chelsea alleged Clattenburg called Mata a "Spanish t**t" in 2012 and John Obi Mikel a "monkey".
The FA opened an investigation but Clattenburg was cleared of any wrongdoing.
Former referees' chief Keith Hackett says: "It's bad news for English reffing. The Premier League has lost the world's best ref - it's a massive blow.
"He's 41 and had nine more years ahead of him - but he's not the first young ref to leave.
"Howard Webb and Mark Halsey both quit early and you have to ask 'what is going on?'
"I think it's down to poor management. There were incidents when the PGMOL (Professional Game Match Officials Limited) haven't supported or clarified decisions when they've needed to.
"Mark felt after the Mata incident no-one supported him. He was left high and dry.
"I was doing lot of talking to him at the time and it's how you manage people and how you manage personalities. That's a part of the skillset that's lacking at the moment."
