The Belgian striker has come down with a bout of second-season-syndrome and United fans are becoming increasingly frustrated with his performances recently.
There have been questions raised about his physicality, with supporters noting his decrease in dynamism and his poor link-up play with his fellow United forwards.
And these same old worries came to the surface during the trip to Merseyside, with Lukaku picking up widespread criticism for his showing.
That was no more apparent than in the Manchester Evening News on Sunday night, when they dished out some pretty ruthless player ratings.
Lukaku's poor performance
Lukaku was branded with a shocking 1/10 as Samuel Luckhurst wrote: "Maybe Alisson fumbled the ball because Lukaku did something. Lost almost every duel with Virgil van Dijk and played amateurishly."
A pretty brutal assessment, but the statistics corroborate his analysis with Lukaku only managed 20 touches at Anfield despite playing all 90 minutes.
That certainly didn't bode well when you consider how routinely Lukaku has been criticised for his touches recently, particularly when it comes to his control.
Lukaku's embarrassing dribble
Games with Crystal Palace, Young Boys and Valencia have seen terrible first touches, but his most recent error came in different circumstances at Liverpool.
That's because Lukaku showed football fans exactly how not to dribble during one moment on the left wing, having actually nailed his first touch.
Also bear in mind that the 25-year-old used almost a quarter of his touches in the game on this one episode of calamity. Check out the video down below:
There's no doubting Lukaku is a top quality player, but nothing is working for him this season and - like the caption notes - moments like this are becoming a weekly occurrence.
And although Lukaku's first touch often takes the headlines, this isn't the first time his dribbling has left plenty to be desired.
During the home tie with Valencia, the Belgian made a questionable attempt at step-overs and finished with the ball tangled under his feet.
Jose Mourinho even touched on the nuances of Lukaku's game after Sunday's defeat, noting: "Sometimes his first touch is not the best and he loses balls in the first touch.
"Today, didn't happen, he had some good link. I think he fought hard, I think he is improving, he played positively the last game against Fulham and today a very difficult match to play, I think he was positive.
"I think he didn't have a bad game at all. He was lively, he had good movement, good interaction."
Do you think Lukaku should start for United? Have your say in the comments section below.