Former United defender Rio Ferdinand wants the club to snatch up Guardiola the moment he becomes available.
Guardiola is being chased by Chelsea and City and he’ll be announcing the next step in his future this weekend.
Guardiola’s contract with Bayern will expire after this season and Ferdinand wants him at United.
“The thing with Manchester United is that he will go to one Premier League team and won’t be going to another [after that],” he told The Guardian.
“There is one chance – you have one chance to get him. He won’t go to Manchester City and then to United; he is not going to go to Chelsea and then United.
“It won’t happen, so you have got one chance to get the best manager on the planet. Is Guardiola better than what they have got? That is what United and City should be asking. If the answer is yes then you go for it, surely.
“It is like with the best players in the world – if someone like Cristiano Ronaldo or Lionel Messi becomes available, everyone is interested. I don’t think it is different with a great manager.
“The best manager in the world is definitely Guardiola and when he becomes available people are going to be interested, and I think United are no different.”
Ferdinand believes the United job is still hugely attractive despite the club’s failure to win a trophy since Alex Ferguson’s retirement in 2013.
“Every manager on the planet, probably bar the man at Manchester City, would love the Man United job,” said the former England international.
“It is a huge job. Especially now, it is a job where, if you go in and do well, you will be seen as a hero – someone who has turned it around.
“It is a tantalising job. It is a job where you could create something with legacy. That is what Pep Guardiola likes to do, but he has got options.
“People talk about Man City, Chelsea, Arsenal. It is not going to be easy.”
Former Barcelona boss Guardiola, 44, has won five league titles and two Champions League crowns since his first-team managerial career started in 2008.