Manchester United take on Leicester City in the FA Cup fourth round on Friday night.

United claimed a gritty win against Arsenal in the previous round of the competition - Diogo Dalot was sent off in normal time - and will now welcome Leicester to Old Trafford.

United knocked Leicester out of the Carabao Cup in October, 5-2 at Old Trafford, and the Foxes lost 3-0 when they returned for a Premier League fixture in November. Ruud van Nistelrooy is now in charge of Leicester and the popular Dutchman will return to Old Trafford for the first since the conclusion of his interim role at United.

READ MORE: How Manchester United should line up vs Leicester in FA Cup fixture

READ MORE: Why Ruud van Nistelrooy left Manchester United after Ruben Amorim appointment

Here are the five things to look out for in the clash...

Regrets over Van Nistelrooy?

Van Nistelrooy probably regrets taking the Leicester job because they look destined for relegation, but could there be a tinge of regret at Old Trafford about deciding they wanted to appoint a permanent manager, instead of allowing Van Nistelrooy to take the team for the remainder of the season?

Ralf Rangnick was the last interim United manager to be given that remit and it didn't work out, but Ruben Amorim hasn't inspired a huge turnaround in form and some have argued it would have better for him to arrive in the summer because he would have been given a full pre-season to implement his system, and new sign players who could actually perform in his formation.

Amorim has been operating with square pegs in round roles. Ineos understood he would implement his system immediately and that he wouldn't have the required personnel, so maybe it would have been better for him to have joined from Sporting Lisbon in the summer?

Van Nistelrooy did a fine job as United's interim manager. Although that doesn't necessarily mean he would have continued to get results, he might not have done much worse.

Amorim has been given an impossible task - United needed to help him in January - and he will be counting down the days until the end of the season so he can sign players for his system.

New boys in the squad

"We’ll see, you guys have to wait until tomorrow, but they are ready to play and are two more solutions in this moment," said Amorim about United's new signings at his press conference.

United paid €30million (£25m) to sign Patrick Dorgu with a potential €5m (£4m) in add-ons, and Amorim confirmed the defender will be available to face Leicester.

It's a no-brainer to start Dorgu at left wing-back, given he's been signed for that role, but supporters might have to wait a little longer to see Ayden Heaven make his debut.

Heaven signed from Arsenal for an undisclosed compensation fee and is seen as a first-team addition, which raises the prospect of the 18-year-old making his debut in the coming weeks, but he has stiffer competition in his position and doesn't have as much first-team experience as Dorgu.

Debut from the academy?

Godwill Kukonki was the only youngster to make an impression on Amorim when he took his first training session at Carrington in November and is pushing to make his senior debut.

The centre-back celebrated his 17th birthday on Thursday and could have a week to remember if he's given an opportunity by Amorim in the closing stages against Leicester.

Kukonki will have to make the squad to do that, of course. He was last named on the bench for the win against Southampton on the Premier League, but he's continued to go from strength to strength in appearances for the academy and it would be a surprise if he hasn't made a debut by the end of the campaign.

United can make history

As mentioned, United have already beaten Leicester twice at Old Trafford this season and Van Nistelrooy oversaw those wins. United have never won three home games against one club in a season before, which means they can make a small piece of history if they progress to the next round of the FA Cup.

Manchester City were the last Premier League side to win three games in a season against a fellow top-flight opponent and United will be looking to brush aside the Foxes with minimal fuss.

Fernandes loves the FA Cup

Bruno Fernandes has been the best United signing of the post-Sir Alex Ferguson era and he loves the FA Cup. Fernandes has been involved in 10 goals in his last 10 appearances in the competition (seven goals and three assists) and popped up with a goal against Arsenal in the last round.

Fernandes also scored a goal and recorded an assist in the 3-0 win over Leicester in the league, and scored twice against the Foxes when they were hammered 5-2 in the Carabao Cup. Simply put, if you're a Leicester fan, you're sick of the sight of Fernandes this season.