Manchester United Transfer News: Latest Marquinhos and Grigoris Kastanos Rumours

Jose Mourinho could battle Barcelona for the services of Paris Saint-Germain starlet Marquinhos, as the Camp Nou giants prepare an offer for the talented defender.

Bleacher Report's Jonathan Johnson cited reports from Brazilian outlets and French newspaper L'Equipe, which said Barcelona remain interested in the Brazilian player, revealing how much they're willing to offer:

According to L'Equipe (h/t Aaron Flanagan of the Mirror), United are also interested in the 22-year-old, who is considered one of he best young defenders in world football. The Red Devils have been linked with Marquinhos in the past, but the player opted to stay with PSG.

The exit of David Luiz to Chelsea has further complicated matters, as the defender has been pushed forward to replace his compatriot in Ligue 1.

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Marquinhos fits the type of defender Mourinho requires, and the manager needs to find a long-term partner for Eric Bailly. The self-proclaimed Special One recently highlighted his development of Raphael Varane at Real Madrid, and explained the recent signing could emulate the coach's previous success with prodigious young centre-backs, per Sky Sports:

"

I will give him [Bailly] everything to try to make him better, like I did with other central defenders I've had in my hands, like, for example, Varane.

I will try to make him the best I can. He has shown the potential we saw when we decided to buy him.

He's a very young boy coming from a completely different environment, but you could see what he is at this moment.

"

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Marquinhos is a closer fit to Varane than Bailly, and has excellent dribbling and concentration—an element missing in United's current central defender stock.

The Brazil international featured 35 times in Ligue 1 and the UEFA Champions League last term, according to WhoScored.com, and would give United a player in the mould of John Stones—fresh for long-term development.

However, Barca will be a difficult opponent for United if they wish to build their defensive options around the PSG man.

Here is the defender in action:

In other news, United might continue youthful pursuits by turning their attentions to Juventus teenage midfielder Grigoris Kastanos.

Italian outlet Juve News (h/t Sam Morgan of the Sun) reported Mourinho could move for the 18-year-old, but will face stiff opposition from Everton for the player. The Cyprus international will be offered a new deal to stay with the Old Lady, but a bid of £17 million could force a transfer.

United have looked brittle in the centre of the park, and the addition of Paul Pogba has not provided an immediate solution to the club's lack of steel or purpose.

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Mourinho will need to continue to develop his core, and the addition of Marquinhos would turn United into a side that is more comfortable in possession, playing out from the back.

The future looked promising only weeks ago, but it has since become evident there is plenty of rebuilding left to do at Old Trafford.