You would never say Arsenal and Manchester United are having similar seasons, but Sunday's Premier League stalemate at Old Trafford was a reminder that they have something in common - a problem to solve up front.

While the Gunners' attacking flaw appears to be a glaring one, in that they have played much of this campaign without a recognised centre-forward, United do have some strikers, but their regular failure to find the net has left people questioning whether they are good enough to help Ruben Amorim's side climb the table.

Wayne Rooney had sympathy for Joshua Zirkzee and Rasmus Hojlund when he analysed their display for his former club on Match of the Day 2, but felt Arsenal's issue again proved costly after watching them lose even more ground to Liverpool in an increasingly one-sided title race.

"I always feel the teams with the best number nines have the best chance of winning things," United's all-time record goalscorer, who won five Premier League titles, told BBC Sport.

"Liverpool are probably an exception to that, with the way they rotate the player they use through the middle, rather than having a regular number nine that the team is built around.

"The number nine is still so important for them, though. Mohamed Salah, cutting in from wide areas, is their main goalscorer but, whether it is Luis Diaz, Diogo Jota or Darwin Nunez in the centre, they all chip in with a good amount of goals."

With Gabriel Jesus and Kai Havertz out for the season and another key attacker, Bukayo Saka, absent, it has been left to midfielder Mikel Merino to fill in as an emergency striker for Mikel Arteta's side in the way he did against United, this time with little effect.

While the Gunners controlled the game for long periods, goalscorer Declan Rice conceded afterwards that they did not have the cutting edge needed.

"A proper number nine - a forward who has played there his whole life - brings something different to any team," said Rooney.

"I am talking about that natural goalscoring instinct, which a player who is trying to learn the position probably doesn't have.

"A midfielder playing forward like Merino can get hold of the ball and bring others into play, but what a goalscorer brings is that selfishness of wanting to be in the penalty area to finish chances.

"As we saw on Sunday, Rice was trying to help Arsenal to fill that position, as the player who was always making forward runs and arriving in the box. He did really well in that advanced role, but he cannot always be there."

Merino may be a midfielder, but he has scored three Premier League goals this year. Hojland and Zirkzee have none.

Those numbers may not suggest the answer to United's goalscoring problems lies within their current squad, but Rooney argues that any striker would find it difficult playing up front for United at present.

"Before they scored at the end of the first half, United had managed one shot at goal and none on target," Rooney said.

"Their problem was their lack of movement in midfield, because they could not make the passes to get up the pitch. Instead, they were forced to play balls up to Zirkzee and it was very hard for him to do anything with them.

"The best centre-halves, like Arsenal's are, force you under the ball in that situation or nick balls off you.

"If the ball is getting chipped in to you around the halfway line, which is what Zirkzee was getting, and you haven't got the support in and around you, then it is very difficult and you have to work extremely hard.

"Firstly, you are fighting the centre-half and holding him off you. Then you've got to get the ball under control and try to bring someone into play.

"If the quality of the pass up to you is not great, especially when it is coming to you around your neck like some of United's passes were, it is even harder.

"A lot of the time Zirkzee was getting given a 50-50 ball, the kind where you have to work wonders to win it. Ideally, what you want is your team to make a few passes and play out of the pressure, then as the striker you are getting the ball to feet, which makes it a lot easier, and you are closer to the opposition goal too.

"For a centre-half, if you are facing your own goal and in your own half, then it makes their job a lot easier, but if you are higher up the pitch the striker has lots more options. The defender cannot be all over you because they are afraid of giving free-kicks away.

"What United needed to do was get some control of the game, and get on the ball. Then the striker can make the little five yard bursts to get behind the defence, which give you a better chance of scoring."

While Zirkzee had few sights of goal in the first half, replacement Hojlund got a couple of good opportunities to end his drought when the game opened up late on - but was unable to take them.

"There was one chance where his shot was blocked after he had shown fantastic movement to get to the near post," Rooney said.

"He goes once, he checks back, goes again, got across Gabriel and got a good contact on his shot, so he had done everything right. It is only a great block that stops the goal."

"The one that will be highlighted, though, is the one where Rice gets back and tackles him after the ball breaks for him in the area, and that was purely down to a lack of confidence.

"You see Hojlund take a touch and then he is looking up to see where he wants to put his shot when he doesn't have the time for that.

"That's the kind of scenario where, as a striker, if you are scoring goals you don't even have to look up - you know where the goal is.

"To me that really showed how much he needs a goal right now, but all he can do is keep working.

"I've got faith in him. He's a good player who works hard, which is really important. He needs that bit of luck as well, but once he gets a break then more goals will follow.

"As a striker for Manchester United, when you are not scoring goals there is a lot of pressure and a lot of people questioning if you can do it for United.

"The best thing for Hojlund to do is simplify it. Making runs into the penalty box is as easy at it comes. There was an attack late on against Arsenal I highlighted on Match of the Day 2 where Alejandro Garnacho is about to put in a cross and Hojlund needs to have that desire to get in the box.

"He goes to go, then for some reason he stops. If he carries on his run then he is in the right place around about the six yard box to get a tap-in for the winner when Bruno Fernandes' shot is saved.

"When you are short of confidence you have got to make sure you make it into the penalty area and put yourself in a position where you can score, so that is something he can improve on.

"We are still waiting to see Hojlund find his feet for United, but it's important to point out that the whole team have not been at their best.

"I feel for him from that point of view because, nine times out of 10, forwards rely on their team-mates for service.

"United have not been playing well or creating enough chances, so he has not been in a team dominating possession, sliding balls in behind the defence or putting balls into the box."

One way for both clubs to solve their attacking issues will be in the summer transfer window, but it is not just United and Arsenal who seemingly need a new striker.

Chelsea are also being linked with a string of number nines, and even Liverpool are supposedly lining up a goalscorer as a potential replacement for Salah, whose contract is up at the end of the season.

Ipswich's Liam Delap is reportedly being targeted by several clubs. The 22-year-old is a player Rooney considered signing in the past, when he was a teenager available on loan from Manchester City in 2021.

"Liam is someone I looked at for the clubs I've been at, and he is a fantastic player," Rooney said. "He is a powerful lad and has a great physique to play the role he does.

"He probably surprised a few people by going to Ipswich, but he has scored some great goals.

"Ipswich are struggling in the league, so it is not always that easy for him, and I have seen a few games where he can get frustrated because he is not getting the service - exactly the problem I was talking about with United.

"But Liam has a massive amount of potential and I am sure he is going to have a fantastic career.

"I can see why the top clubs are being linked with him, but they are all going for the same players, because there is a shortage of number nines."

It does seem like the same strikers are on the summer shortlist of several clubs.

Arsenal failed with a January bid for Aston Villa's Ollie Watkins, while Crystal Palace's Jean-Philippe Mateta has been talked about as a target for the Gunners and United.

"Mateta is a big, strong lad who scores a lot of goals," Rooney said. "From watching Arsenal over the past few games in the Premier League, they have put a lot of balls into the box without having anyone to get on the end of them. I am sure he would help from that point of view."

As well as finding someone who suits your playing style, availability is another obstacle.

Newcastle's Alexander Isak is often viewed as the answer to Arsenal's lack of strikers, and he has also been touted as a potential Salah replacement.

"Isak would fit into any team," Rooney said. "He has been fantastic over the past couple of years and scored a lot of goals. His link-up play and movement is brilliant too.

"You look at any team in the Premier League, and whether it is United and Arsenal or Liverpool then he would improve them, but I also think it will be very difficult to get him out of Newcastle. Why would they sell him?"