Benitez’s side take on the League Two club in a third-round tie at St James’s Park on Saturday.
United’s manager made nine changes for the club’s last FA Cup game – the 3-0 fourth-round defeat to Oxford United almost a year ago – and Benitez will again use his fringe players in the competition.
The tie is followed by an important home league game against Swansea City on January 13.
Newcastle go into the Luton game on the back of a positive run of Premier League results over the festive period.
Man in life-threatening condition after 'serious collision' involving car and pedestrian in South Shields
Campaigners rally against Local Plan after farmland in Cleadon earmarked for 156 homes
Appeal to find owner of lost Labrador after dog found near Jarrow Cemetery
Pair set up cannabis farm in town centre flat
South Shields man jailed for terrifying physical and sexual assault on woman in her own home
United climbed up to 13th place after their 1-0 win over Stoke City on New Year’s Day.
However, Benitez – whose side was knocked out of the Carabao Cup by Nottingham Forest in August – is approaching the FA Cup with caution.
Asked if the cup was a welcome distraction for him and his team, Benitez said: “Not really.
“We have two or three injuries, maybe they will need some time. We don’t have too many players.
“Playing two games in a few days, we needed to change players (against Stoke).
“To play more games is not ideal. OK, we have to do it and we will do it.”
Benitez is without Aleksandar Mitrovic (back), Florian Lejeune (foot) and Jesus Gamez (ankle).
A number of other players have been carrying knocks through the festive programme.
Meanwhile, Luton – who beat Lincoln City 4-2 on Monday – have been given a huge 7,853-ticket allocation for the game. They expect to sell all their tickets.
The club is four points clear at the top of the League Two table.
Luton manager Nathan Jones took over at Kenilworth Road two years ago.
“It’s not a bad place to celebrate your second anniversary, going to St James’s Park and pitting your wits against Rafa,” said Jones.