Man Utd could be forced to axe popular player because of controversial rule few know about

Michael Carrick is facing an uncomfortable conversation with one of his Manchester United players if they complete one signing in the summer transfer window.

United finished third in the Premier League last season and qualified for the Champions League for the first time in three years.

The club will bolster their squad ahead of a return to Europe's elite competition, with Atalanta midfielder Ederson expected to arrive after the World Cup.

Other midfield targets include Mateus Fernandes and Alex Scott, while Crysensio Summerville and Lewis Hall have also emerged as potential left-back and left-wing reinforcements.

A position that won't excite supporters, but requires addressing, is the backup goalkeeper position. Senne Lammens is the undisputed number one, which means Altay Bayindir will be allowed to leave Old Trafford.

United are looking to replace him with Leeds United shot-stopper Karl Darlow. His contract expires at the end of this month and Leeds boss Daniel Farke can't guarantee he'll be number one next season. A move to the Red Devils would give Darlow an opportunity to play Champions League football, as well as a pay rise.

READ MORE: Ex-Man Utd boss Ruben Amorim lines up £85m double swoop on former club

Why signing Darlow would be a disaster for Ayden Heaven

An unexpected casualty of Darlow's arrival would be young centre-back Ayden Heaven. The 19-year-old has impressed since arriving from Arsenal in February 2025, making 19 appearances in all competitions last season. He started in three consecutive wins over Chelsea, Liverpool and Brentford towards the backend of the season as United battled injury and suspension issues at the back.

Heaven has established himself as the perfect deputy for Lisandro Martinez and Harry Maguire, with Matthijs de Ligt recovering from a back injury and Leny Yoro struggling to adapt to English football.

Despite all that, he could find himself out of United's squad for the Champions League due to UEFA's rules on player registration.

Despite being under 21, Heaven doesn't count as a homegrown player yet, as he's only been at United for 16 months and counts as being nurtured outside of the club's system.

It means he would potentially face being axed from the club's Champions League squad when it's announced later this year.

Simon Stone of the BBC explained the situation to The United Stand and suggested the club could sign ex-United academy star Sam Johnstone from Wolverhampton Wanderers to bypass the issue.

He said: "I've seen Karl Darlow's name being mentioned. But there's just one issue, I read up on it today to make sure these facts align.

"In the UEFA 25-man squads for European competition, you can have a maximum of 17 players who have been 'nurtured' outside of your association.

"Of those eight [other] places, a maximum of four is for players trained at clubs other than yours, and four for players who have come through your system, and are over 21. Ayden Heaven is another one who came through Arsenal's academy, and although he's under 21, he's not been there for two years yet.

"That is the reality. I've seen Sam Johnstone's name mentioned; he'd be counted as a homegrown player because he came through Man United's academy...

"If Karl Darlow came in, he's an English player but was developed somewhere else. Would that mean you'd bring someone in and it means Ayden Heaven, for instance, couldn't be registered for European games because he's not a club-trained player?"