And former Liverpool defender and ESPN FC TV pundit Steve Nicol has laid into the Belgian, claiming he’s a flat-track bully.
Lukaku arrived at Old Trafford this summer in a whopping £75m deal from United’s Premier League rivals Everton.
And he hit the ground running in Manchester, silencing the critics that had claimed he was overpriced.
Lukaku has since endured a barren run though, netting just twice in 13 games in all competitions.
And Nicol has torn into the 24-year-old after he failed to shine in United’s 2-1 defeat to local rivals City.
"He didn’t go missing, he was there, front and centre, whether it was defensively, or whether it was attack," Nicol told ESPN FC TV.
"He’s got an opportunity to shut people like me up.
"He’s seven yards out, he’s got a free shot, he can put it anywhere and, what does he do? He hits it straight at the goalkeeper, straight at him.
"You can’t tell me that’s £90m worth [of talent].
"He’s so far proven me and everybody else right.
"He’s a bully against teams that are just scared of Manchester United and not necessarily Lukaku."
Claims of a post-match fracas between United and City players have emerged in the aftermath of the Premier League showdown.
And Nicol used the example of a City member of staff being hit by a plastic bottle in those clashes to take another swipe at Lukaku.
"It wasn’t Lukaku that threw it if it hit him," he added.