A former colleague has warned Julian Nagelsmann against taking over at Manchester United - 'where essentially every manager in recent years has failed sooner or later.'

Nagelsmann, 39, is on a five-man list of managers who have been privately sounded out to replace under-pressure Michael Carrick at Old Trafford.

But Oliver Kahn, the legendary Germany goalkeeper who served as Bayern Munich's CEO during Nagelsmann's period as manager, is warning his countryman a move to Old Trafford may not be a good fit and is an 'enormous risk'.

Carrick's days as manager look numbered after United were beaten 4-1 by Como in the Champions League this week - and he could join a graveyard of managers featuring Ruben Amorim, Erik ten Hag, Ole Gunnar Solskjaer, Jose Mourinho, Louis van Gaal and David Moyes since Sir Alex Ferguson retired in 2013.

Kahn identifies that history - and Nagelsmann's own past - as reasons not to move to the Premier League. Nagelsmann has managed Hoffenheim, Leipzig, Bayern and Germany but was sacked in his last two jobs amid concerns about his style of communication and approach to training.

Kahn himself said Bayern's squad was playing 'less successfully and less attractively' under Nagelsmann when he sacked him three years ago.

Speaking on German television this week, Kahn sent a warning to Nagelsmann saying: 'From his point of view, it's not an easy situation. He isn't someone with a great deal of experience, particularly when it comes to foreign teams.'

On the RTL/Sky Germany show Triple - der Hagedorn Fußballtalk, Kahn went on to add: 'The Premier League and Manchester United have not been known for much continuity in the managerial position in recent years.

'He has to ask himself: What is my next step? Does it have to be the right one? Or do I immediately associate it with an enormous risk like Manchester United, where essentially every manager in recent years has failed sooner or later? You should look very carefully at where you're going.

'Bayern Munich and the national team were already big blows for him. You have to think carefully: Where do my strengths lie? Which club can I really help? I think Julian is someone who can develop a club and a team and take them further. Whether Manchester United are the right next step for that is something only he can know.'

Yesterday, Daily Mail Sport revealed United's director of recruitment Christopher Vivell is pushing hard for Nagelsmann to be the leading candidate, with the ex-Bayern boss out of work following a disastrous World Cup in charge of Germany. 

Chelsea assessed Nagelsmann as a potential manager when Vivell was technical director in west London and his admiration remains.

But sources have suggested that Jason Wilcox, who is Vivell's boss in the chain of command, prefers a Premier League proven manager, with Eddie Howe, Fabian Hurzeler, Unai Emery and Antonio Conte, who have all come up on a shortlist, a tick in that category.

Hurzeler does not have a release clause in his Brighton contract and so would require enormous compensation. There is well-placed scepticism as to whether any move would even be remotely possible, regardless of how well liked he is inside Old Trafford.

Carrick will face the music when he addresses the media today in his pre-match press conference ahead of Sunday's game against Bournemouth in which he'll have to address doubts creeping in from players, tensions upstairs among execs and whether he will be able to keep hold of his job.

United are refusing to press the panic button and sack Carrick who is now expected to stay in charge for Sunday's game against Bournemouth at Old Trafford at least. United then face Chelsea, Roma and Aston Villa before a two-week international break next month.

The fact that Carrick will speak to the media again, less than two days after he tried to explain his team's shocking performance in the Giuseppe Sinigaglia Stadium, is the strongest signal yet that United are aiming to stand by Carrick for the time being.

In-fighting at United is rife right now, not least after captain Bruno Fernandes publicly questioned the tactics of his manager after the abject 4-1 defeat at the hands of Como.

'It needs to start at the top,' one source close to a first team player said. 'Recruitment guys, manager, the lot need to go.'

Another source said: 'This needs a strong board to make hard decisions fast. They've already wasted too much time.'

United have stressed that Vivell and Wilcox maintain a healthy relationship even in such trying circumstances, but many close to the dressing room are telling a different story.

'At this club, there's too much focus on what's been done in the past, but we're not those people anymore,' Fernandes told Sky Italia after the Como defeat.

'The club and the players need to understand that. Unfortunately for us - especially when it comes to the players - those who join expect to win trophies, win games, and reach the highest level, but unfortunately that's been very difficult at this club in recent years. That's the situation.'