"I am expecting the manager to get sacked before Christmas," the -year-old, who won three Premier League titles with United, told Sky Sports.
"If he is going to continue with this dourness and this moaning, then people will turn around and say this attitude is not getting us to the top so we need to change it.
"It just seems same old same old. As much as the press and fans have been on Jose Mourinho's case about the negativity over the past few seasons and him moaning about players he has and has not got, he just seems to ignore everybody and carry on as usual. He looks fed up and it is reflecting in his team's performances. He is playing negative stuff.
"As a player, you come back for pre-season, you've had a break and you've missed football by the time you come back. You're excited and you're eager. You're like a schoolboy again. To then come back and have a lot of negativity and dourness around the place is not great. It is just not a nice way to start the season. It looks like it could be a long slog.
"I just think the way he is going about his business, I don't think he is getting the best from the players. This team has some unbelievable attacking players but I don't think they are on the front foot enough, I don't think they are playing at a quick enough tempo and I don't think they move the ball enough. They give teams a chance to get back and get organised.
"He has so many options going forwards, it is a shame that he wants to play the way that he wants to play. It didn't work last year against a rampant Manchester City and if things aren't working you have to learn from your mistakes and change something. He needs to change but he just seems to be too stubborn to alter his approach."