That is the fear of ex-United captain Paul Ince, who says the same happened in the final year of his second spell with Chelsea when the defending league champions went on to finish 10th after his sacking.
Mourinho’s future at Old Trafford has been subject to speculation due to a rocky Premier League campaign.
The Red Devils are 12 points off of league leaders Manchester City and seemingly out of the title race already while their hopes of Champions League qualification are already somewhat bruised given they sit seven points adrift of the top four after just 12 games.
Mourinho was even tipped to be sacked in early October ahead of a clash with Newcastle, though United won that game from 2-0 down and went on to win three straight matches before the Manchester derby.
United were soundly beaten by their neighbours at the Etihad before the international break and Ince thinks it may be a sign Mourinho has lost his players.
Talking to Paddy Power, the former midfielder said: “It’s worrying that, at the end of Mourinho’s time at Chelsea, players stop wanting to play for him.
“We’re potentially seeing that here at United now too.
“Personally, I don’t understand the attitude of refusing to play for a manager when you have thousands of fans who want to see you play, too.”
Paul Pogba was a huge miss away at City with United lacking his ability to carry the ball up the pitch and create chances.
But Ince actually thinks Pogba should be sold if his former club can recoup the club-record £89million they spent on him two years ago.
That’s with Pogba linked with Barcelona having been a transfer target for the Catalan club in the summer.
He added: “I can’t say I’m surprised to hear about the Paul Pogba rumours, suggesting he’s interested in leaving Old Trafford in January.
“He said recently that he was happy at Man United, but I didn’t believe any of that.
“What worries me though is that we saw in the Manchester derby how much United miss Pogba when he isn’t available.
“So, yes, the club will have to think carefully about whether they’re happy to let him go, though I’d say his behaviour over the last year or so would make that decision easier.
“I believe a Pogba move away from United would suit both parties. If we’re being honest, he’s never settled on his return to the club.
“He’s been inconsistent in his performances, going from world class to looking bang average, and there’s always been whispers and transfer talk surrounding him in that time.
“Some of those rumours have come from his camp, too. As long as he’s at United, there will be trouble and talk about him wanting to leave. It wouldn’t surprise me that if the money was right United will let him go.”
United return to action after a fortnight off at home to Crystal Palace tomorrow (3pm).