Manchester United manager Jose Mourinho should not start Romelu Lukaku back in the Manchester derby on Sunday.
That is according to former United player and Class of 92' star Ben Thornley.
Lukaku has been injured for United's last two victories over Bournemouth and Juventus.
The Belgian returned to training on Friday and Mourinho confirmed he would be available for selection if deemed fit.
But Thornley thinks Mourinho would be making a mistake if he altered a winning team to accommodate United's £75m signing.
He told TribalFootball.com: "If you're asking me, I wouldn't tamper to much with a team that has just come off the back of beating Everton, beating Bournemouth and winning in Turin. He wasn't present in two of those games.
"And he hadn't hit the heights of last season anywhere close up until that point, so to bring him back for me would not be the right thing to do. Jose Mourinho is looking like he's got a bit of a winning formula while he's been absent and I think he should just stick with that. You don't really change a winning side and I don't feel even though we're going to the Etihad that he should do that."
United will head across Manchester as heavy underdogs against Pep Guardiola's side, who sit two points clear at the top of the Premier League table.
Mourinho is expected to employ defensive tactics to nullify City's potent attack and Thornley believes that starting Alexis Sanchez, who impressed in Lukaku's number nine role against Juventus, would benefit United on the counter-attack.
"I think that we're going to spend a lot of time without the ball, therefore we need to have the explosive players to play on the counter-attack. And when you think about that, you think about people like Paul Pogba, Anthony Martial, Marcus Rashford.
"And yeah, let's follow on with Alexis because he didn't do so much in the game [against Juventus], but he had so much energy and he was closing down, he was winning the ball back and linking up the play really, really nicely. And if we can get Alexis back to the form he showed at Arsenal, then we will have a hell of a forward line."