Former Real Madrid assistant coach Paul Clement has described Sergio Ramos as one of the best players he has ever worked with.
Clement worked with the defender for two years at Madrid before becoming Derby County boss.
And Clement, who has worked as an assistant coach at Chelsea and Paris Saint-Germain, believes the 29-year-old is one of the best centre-backs in world football.
He told Sky Sports: "He is a wonderful player, one of the best I have ever worked with.
He is one of the best centre-halves in the world and I’ve worked with some good ones like John Terry and Thiago Silva.
"So many qualities, a fantastic footballer, leader, competitor, athlete, a fantastic guy.
"He is one of the best centre-halves in the world and I've worked with some good ones like John Terry, Thiago Silva at PSG, good ones in Pepe and Raphael Varane but Ramos is up there with the best I've worked with.”
The former PE teacher added: "Whether at Real Madrid or United, either club are going to massively benefit.
"Wherever he is, it's going to a massive plus for that club."
Ramos has two years left on his contract with the 10-time European champions.
The World Cup winner told Madrid earlier this week he wanted to leave the club and speak with United, according to Sky Sports' Spanish expert Graham Hunter.
Former Real president Ramon Calderon said he believes the defender only wants to join United after becoming frustrated with the Spanish giants over his contract.