Lingard, 28, has been simply stunning since joining West Ham United on loan in January, having scored eight goals in nine appearances.
And Ighalo, who spent a season on loan at United with Lingard, thinks his former teammate could leave on a permanent basis.
"But when you play for a team like Manchester United, there's a pressure to win every game.
"Manchester United is all about winning, winning, winning, and sometimes that pressure kicks in.
"West Ham is not as big as Manchester United and he's there on loan so he's more free to express himself.
"There's not as much pressure or weight on him to do well and he is doing what we know he can do and we are seeing the best of him."
"But if he comes back with the confidence he has now, then it can only be a good thing for Manchester United.
"Personally, I don't see him coming back - I can see his loan being extended or West Ham buying him."