The decision comes amid concerns over his suitability in the new 3-4-2-1 formation preferred by manager Ruben Amorim.
Mainoo, who broke into the first team under Erik ten Hag, made a significant impact last season, featuring in 32 matches across all competitions. His performances were instrumental in securing the FA Cup, but his role has diminished since Amorim's arrival. His versatility, previously highlighted by his box-to-box capabilities, seems not to fit well in the current tactical setup.
The young midfielder's struggles were evident in a recent match against Crystal Palace, where an attempt to utilize him in a more advanced role fell flat. This has led to speculation that United's coaching staff might be more open to his sale than ever before.
The contractual situation adds another layer to this saga. Mainoo's current deal, signed in February 2023, is due to expire in 2027, with an option for an additional year.
His weekly wage of 25,000 pounds significantly undervalues his current market standing, especially post his notable performances for both club and country, including starting all four knockout matches during England's campaign at Euro 2024.
Interest from top clubs is no surprise. Chelsea have long admired Mainoo, but now Bayern Munich have also entered the fray for the 19-year-old's signature. Fabrizio Romano, in a statement last month, acknowledged the widespread admiration for Mainoo, stating, "How can you not love a talent like Kobbie Mainoo?"
Meanwhile, Manchester United's transfer strategy this winter included sending Brazilian winger Antony on loan to Real Betis, where he has since thrived, indicating perhaps the environment at Old Trafford wasn't ideal for all players. This could serve as a cautionary tale for how they handle Mainoo's potential departure.
As United look to rebuild the squad, the sale of Mainoo could fund new acquisitions, with interest also shown in Atalanta's striker Mateo Retegui. The club's transfer activity remains a focal point, especially after a bid for Barcelona's Fermin Lopez was rejected in the winter window.
Mainoo's departure would be a significant moment for United, potentially marking the end of a promising chapter for one of their brightest academy products. His attributes, composure, press resistance, and flair, have drawn comparisons to the likes of Toni Kroos and Rodri by former United star Paul Scholes, who praised, "I think Kobbie Mainoo has got the ability to do that."
Roy Keane, another club legend, also commented on Mainoo's rapid development, saying, "You see the stuff he is doing, I played in that position, but he's doing stuff that probably took me 10 years to learn."
As the summer transfer window approaches, all eyes will be on how Manchester United manage this situation, balancing the need for squad evolution with retaining their homegrown talent.