These are, of course, unprecedented times, although Ole Gunnar Solskjaer discovered there are some things that simply do not change.
Juan Mata remains a delightful footballer at the age of 32, with an ability to illuminate and influence any contest, and Manchester United will usually get a penalty.
These two reliable old forces combined in Solksjaer’s favour at Kenilworth Road.
Juan Mata scores Manchester United's first goal of the game from the penalty spot after Brandon Williams was brought down
Marcus Rashford celebrates with his Manchester United team-mates after scoring the goal that sealed the result for his team
Mason Greenwood scored a goal in second half stoppage time to help the score line flatter Manchester United more
Mata flickered, sparkled and scored from the spot, just before half time, and it put United in control against spirited Luton Town of the Championship.
It was United’s 23rd penalty in all competitions since the start of last season.
They have converted 19 of them, and this was the one to help their season creep into life, after a belated start and an unexpected home defeat against Crystal Palace.
Luton refused to yield until Solskjaer sent on Bruno Fernandes, Marcus Rashford and Masno Greenwood and added gloss to the score line with two late goals.
Rashford claimed the second, in the 88th minute and Greenwood added the third, which added gloss to the scoreline and secured a place in the fourth round of the Carabao Cup.
Dean Henderson made the start for Manchester United, as he competes for the job with usual number one David de Gea
Henderson's first Manchester United save was an excellent one, diving to his right to deny Luton Town an equaliser
Solskjaer made 10 changes to the team beaten by Palace on Saturday, with recalls for some of his forgotten squad men, including Jesse Lingard, who opened brightly, and Mata, who tested Luton goalkeeper James Shea twice inside the opening quarter of an hour with lows shots from the edge of the penalty area.
Manchester United started at a brisk tempo and dominated possession. Fred whistled a shot narrowly wide but Luton did not come into the tie to defend and were bubbling with confidence after performing a stunning escape from relegation last season under returning boss Nathan Jones, and starting the new campaign with four wins on the bounce.
Jones, like Solskjaer, made wholesale changes to his team, with only two surviving from the win against Derby on Saturday. They weathered United’s early efforts, grew into the game and began to threaten the United goal.
Danny Hylton, released by Ryan Tunnicliffe, was disappointed to slice a shot wide