Goals in either half from Bryan Mbeumo and Bruno Fernandes were enough to give the Reds the three points, who put on a confident display the day following the 68th anniversary of the Munich Air Disaster.
The visitors had been reduced to 10 men with less than 30 minutes played, when Cristian Romero was dismissed for a mistimed challenge on Casemiro.
A debut for Tyler Fletcher, towards the end, capped another enjoyable afternoon at Old Trafford.
FIRST HALF - MBEUMO MAKES DIFFERENCE
In his fourth game in charge, Michael Carrick named an unchanged XI from the side that beat Fulham the previous weekend, with match-winner Benjamin Sesko remaining on the bench.