The Belgian forward headed the visitors into the lead in the 27th minute when he turned home Marcus Rashford’s cross.
Jesse Lingard then made it 2-0 to Jose Mourinho’s men in the 35th minute when he fired home, before Gareth Barry set up a tense finale by netting 13 minutes from time in the second half.
Lukaku has been criticised for his form for Manchester United since his move to the club from Everton in the summer transfer window.
However, the forward has scored 10 Premier League goals since his switch to the club.
Redknapp was very impressed by Lukaku’s goal in the first half on Sunday afternoon but admits he cannot understand why the striker did not celebrate the goal.
Speaking during Sky Sports‘ coverage of the game, Redknapp said: “When he gets the right delivery, he’s unstoppable.
“It’s a great header, he just turns it into the net.”
He continued: “I don’t get the non-celebration, I’ll never understand that. Whether he’s unhappy with the criticism he’s been getting… it’s irrelevant. He’s paid big money to affect games for Manchester United.
“Not celebrate a goal? I’d do anything to go a score goals again! And he doesn’t want to celebrate it. I’ll never get it.”
Manchester United’s win left them in second place in the Premier League table and 11 points behind Manchester City.
The Red Devils will return to Premier League action next weekend with a trip to Leicester City in the top flight next Saturday night.
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