Paul Pogba is not a special Manchester United player like Eric Cantona or Ryan Giggs were, according to former manager David Moyes.
Moyes, who managed United for under a year before his Old Trafford sacking in April 2014, does not believe Pogba can make a key difference in the biggest matches.
Moyes does not feel Pogba, 24, belongs in the highest bracket of players.
"I think he's a top player, [but] I don't know if he's a player who completely makes a difference for Manchester United," Moyes said to ESPN.
"I think that over the years Manchester United have had players like Cantona, even Ryan Giggs, people who are special players.
"I don't know if Pogba's that. I think he's a good player, I think he'll add to Manchester United, but will he make the difference?
"Is he someone who will score the goal at really important stages in games or make the key pass? I'm not sure about that.
"But I do think that the machine that Manchester United are now, the size, the players they've got, you know they've got a massive stature to their team, I think Pogba adds to that.
"And I do think he's a good player, but I'm not quite sure if he'll make the difference in key games."
Current boss Mourinho disagrees with Moyes, having claimed last month the midfielder is on the same level as Lionel Messi, Cristiano Ronaldo and Neymar after his fine pre-season form.
United open their Premier League season at home to West Ham on Sunday.