Four of the game's five goals came in the first half, as Pogba scored twice and Rashford added a third for the hosts prior to Ake pulling one back.
Any lingering hopes of a comeback from Howe's men were ended by Lukaku, who found a way through for his side's fourth of the contest just two minutes after being introduced form the bench.
Bailly was dismissed 11 minutes from time for a bad challenge on Fraser, but United did not look under any sort of threat in the remainder of the match.
Ander Herrera, Eric Bailly and Ashley Young were the others coming in, with Juan Mata and Phil Jones demoted to the bench and Fred and Dio
And United needed just five minutes to open the scoring.
Marcus Rashford beat two defenders and delivered a cross that Paul Pogba turned home from close range.
The Frenchman then made it 2-0 just after the half-hour mark with a firm header and Marcus Rashford added a third before Nathan Ake pulled one back on the stroke of half-time.
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