With Manchester United a long way from recapturing the Premier League trophy they once almost took for granted, the club's struggles to even secure a top-four finish this season suggest that it's going to take more than just a few transfers to catch up to the likes of Liverpool and Manchester City.

However, the United squad needs quality reinforcements as soon as possible and to compete with Europe's elite again they need to bring in proven talents who can perform straightaway. They'll need deep pockets for transfer fees and wages, but paying extra for established stars that can have an immediate impact is more cost-effective than a cheaper alternative who won't offer much of an upgrade on what they already have.

With that in mind, here are six players, aged 23 or younger, who would strengthen Man United's team immediately. (All transfer values taken from Transfermarkt.)

Jules Kounde, €60m

Age: 23
Position: Centre-back/right-back
Club: Sevilla

With Chelsea out of the running while Russian owner Roman Abramovich's assets have been frozen by the U.K. government, this summer might be the ideal time for United to move for Kounde as his contract expires in 2024.

For a team struggling to play out from the back because their current defensive line was not built for that purpose, Kounde would be an ideal acquisition. Few top-level European centre-backs can match the France international's ability to pick the right pass while under pressure, and Sevilla have configured their team to suit his eagerness to bring the ball out of defence and join in further up the pitch.

In the defensive phase, his mental quickness and ability to read danger allows him to make early interceptions. Though still relatively untried in the position, there's also no reason why Kounde shouldn't be able to perform to a high standard at right-back as well. United's defensive woes are not restricted to the heart of the defence and it may prove useful to sign a versatile player who can assist on the right as well.

Sevilla may want closer to €80m but United should be able to negotiate that down, or add a player like winger Anthony Martial (who is on loan at Sevilla) into the deal.

Ronald Araujo, €40m

Age: 23
Position: Centre-back/right-back
Club: Barcelona

While Kounde is an elegant defender who rarely goes to ground to win the ball, Araujo is more of the "whatever it takes" kind. Since making his Barcelona debut in the summer of 2020, the Uruguay international has progressed a lot and has blossomed since Xavi took over.

From being coy and at times clumsy with the ball, especially under pressure, Araujo has learned to adapt his passing game to his own limitations, often going for the safe option of playing into wide areas instead of the congested middle. The quick, brave and physically robust defender is perhaps more comfortable as an out-and-out right-back in a back four, rather than as one of three centre-backs, as he showed in the 4-0 win over Real Madrid last weekend.

His headed goal in El Clasico also provided a fine example of his immense aerial ability; his excellent leap and heading technique make him extremely useful on both defensive and attacking set-pieces. Araujo's contract with Barcelona runs out at the end of next season and, while he is likely to pen an extension given his impact under Xavi, United may sniff an opportunity to land him for a cut-price fee as the financial troubles at Camp Nou continue.

Declan Rice, €75m

Age: 23
Position: Defensive midfield
Club: West Ham

Fast approaching his 160th Premier League appearance, Rice is already among the country's elite defensive midfielders. From his debut in 2016 there's been such a constant development in tactical, physical and technical ability that it's hard to pinpoint an obvious flaw in his game.

Mainly praised for his defensive contributions -- winning the ball back, shielding the centre-backs, breaking up the play and keeping it simple when in possession -- Rice has become more positive in his passing game and now carries the ball forward more. The fact that he has started practically every game since he became a regular in 2018, and never gets substituted whenever there's something at stake, shows how much of a consistent performer he has become.

While West Ham's Champions League ambitions mean Rice won't be an easy negotiation, paying a premium for the England international may ultimately be a sensible strategy -- especially as, despite Fred's improved form, United really need a quality No. 6 to reinject some steel and strength into their midfield.

Aurelien Tchouameni, €50m

Age: 22
Position: Defensive midfield
Club: Monaco

If Rice proves too expensive or hard to sign, it might be worth United shifting their attention to Monaco's supremely talented midfielder. Tchouameni features a skill set not too far removed from West Ham man and recent reports suggest that he might be made available in the summer, with Bayern Munich and Real Madrid also interested.

The France international was outstanding in Monaco's 3-0 home win against Paris Saint-Germain at the weekend. He dominated the midfield as a traditional "No 6" and won 80% of his challenges, while denying Marco Verratti and Leandro Paredes space, as well as playing sensible, measured passes (95% accuracy.)

Arguably Monaco's most important player, Tchouameni can dominate the middle of the pitch but would have no problems deputising at centre-back (in a back three or four) either.

Victor Osimhen, €60m

Age: 23
Position: Striker
Club: Napoli

With Manchester United forwards Cristiano Ronaldo and Edinson Cavani nearing the end of their careers, Marcus Rashford out of form and Mason Greenwood suspended after his recent arrest, the club are struggling for depth up front.

United are ostensibly out of the running for the two top young goal scorers in Europe this summer -- Haaland and Mbappe -- and there are few centre-forwards who come with a guarantee of goals in the current market.

Osimhen, however, is developing into a striker of the highest order, despite not having reached peak fitness all season due to injuries. Napoli signed the Nigeria international for €70m from Lille in the summer of 2020 and he has scored 25 goals in 55 games since. The Italian club are unlikely to let him leave for less than €100m given his contract has another three years left on it, but his development trajectory could make that a bargain.

Already blessed with the ability to outpace high defensive lines, Osimhen has developed his poaching instinct and knack of picking the right spaces in the penalty area. Admittedly, there's still work to be done on his hold-up game -- he needs to be more involved in the build-up phase -- but he has become more diligent in his pressing duties under Luciano Spalletti and has become an increasing target for crosses, often making the most of his remarkable leaping ability.

Darwin Nunez, €40m

Age: 22
Position: Striker
Club: Benfica

Still a work in progress, the Uruguay international has had a breakthrough season in the Portuguese league and is currently top scorer with 20 goals from 22 appearances. Nunez has also impressed in Europe with four goals in eight games, and scored the all-important goal that saw Benfica knock out Ajax to proceed to the Champions League quarterfinals.

A €24m signing from Almeria in 2020, the 6-foot-2 striker is still a bit rough around the edges and his passing can be sloppy, but it's his continuous development and unconventional technique that makes him exceptionally exciting. His choice of positioning in the build-up phase is sometimes unorthodox -- he often disconnects with the rest of the team to do his own thing -- but he can score from a wide variety of positions and the fact that he hits target with close to 60% of his shots is particularly impressive.

When he faces goal, however, Nunez really comes to life, utilising his speed, strength, power and balance to break through on goal. His transfer fee is increasing almost as rapidly as his progression though -- with Benfica reportedly ready to reject anything less than a €80m offer -- so it may be wise for United to make a move for him sooner rather than later.