Pep Guardiola has been warned that he will not find it easy to be successful in England by former Manchester United manager Sir Alex Ferguson in an interview with Sky Sports.
Bayern Munich boss Guardiola will take over as Manchester City manager this summer and Ferguson praised his coaching ability and said the appointment is a coup.
However, the 74-year-old, who won 13 Premier League titles, says Guardiola will not be able to replicate his success at Barcelona where he won thee La Liga titles and two Champions League trophies in three years.
Ferguson said: "Without question Pep has got a fantastic work ethic about him, he demands that from all of his training sessions.
"Anyone who thinks they're not going to work hard at City won't last long. He has got great coaching ability, there is no doubt about that.
"Man City have made a real coup in getting him but Pep won't find it easy, English football is not easy.
"Every foreign coach that has come to England will tell you that. Arsene Wenger was talking about that a few months after coming and even Jose Mourinho was.
"Pep will be a success but I don't think he'll ever replicate what he did at Barcelona because that was a high standard -- they were the best."
In his autobiography "Leading," Ferguson revealed he had wanted Guardiola to be his successor when he left Old Trafford but the Spaniard instead headed for Munich the following season.
He will finally arrive in England this summer -- potentially after winning three consecutive Bundesliga titles -- and Ferguson warned that it is no guarantee that City will win the league and that their rivals, including United, will improve.
He added: "You have to ask what the big clubs are going to do. If you take my time at United, when Chelsea and Jose came on the scene, in the first two years they had quick starts, so I had to accept that challenge.
"That's what you have to do when you're a big club. Arsenal, Liverpool and the other clubs have to accept the challenge when they are not good enough.
"They'll have their own ambitions and will be desperate to win the league next season as much as City, so Pep there is not a guarantee they can win the league.
"That's the beauty of our league. Arsenal, City, Liverpool, Chelsea, Tottenham will want to do something and now, of course, Leicester City are there. Who's to say they can't win it next season?"