Manchester United have offloaded a lot of talent over the last couple of seasons, as the club looks to raise transfer funds and clear the already expensive wage bill.
Players such as James Garner and Anthony Elanga came through the Carrington Academy before both being sold over the last couple of summer transfer windows.
The pair have both excelled after their respective permanent moves to Everton and Nottingham Forest, with the Red Devils potentially regretting letting the duo leave for a combined £24m.
Erik ten Hag's side have been desperate for defensive reinforcements this season, after injuries to the likes of Harry Maguire, Lisandro Martinez and Raphael Varane.
United might have been better off keeping a youngster who they sold on the cheap during the summer, with the former Red Devils man in brilliant form so far at his new club.
Teden Mengi's stats at Manchester United
After joining the club at the age of just seven, defender Teden Mengi signed his first professional contract in September 2019, with the youngster having a big future ahead of him at the Theatre of Dreams.
He subsequently made his United first team debut in the Europa League clash against LASK in the 2019/20 campaign, before being loaned out to Derby County to gain valuable game time.
However, a hamstring injury cut his spell short, with the youngster only making nine appearances for Wayne Rooney's side.
Mengi would recover from his injury to join Birmingham City for the 2021/22 Championship season, but a recurrence of his hamstring problem saw his spell in the West Midlands come to an abrupt end, after just ten appearances in all competitions. Despite that, boss Lee Bowyer still found the time to hail his "outstanding" displays.
His two injury-hit campaigns would see him feature for the Red Devils' U21 side in the Premier League 2 for the 2022/23 season, before being permanently sold during last summer's transfer window.
Mengi's sale would bring an end to his 14-year affiliation with United, with the 21-year-old joining newly promoted Luton Town – a move that would allow him to flourish and show glimpses of his potential.
Teden Mengi's market value in 2024
Seven months after he departed Old Trafford, centre-back Mengi has seen his value soar, with the youngster rapidly developing under the guidance of Hatters boss Rob Edwards.
Although he signed for an undisclosed fee, the 21-year-old's market price has risen from £1.7m when he left United to £10.2m as per Transfermarkt – a remarkable increase of over 500% to his highest-ever market value.
July 2020
Manchester United
£850k
March 2021
Derby County (loan)
£1.2m
December 2021
Manchester United
£1.7m
May 2022
Birmingham City (loan)
£1.7m
June 2023
Manchester United
£1.7m
December 2023
Luton Town
£6m
March 2024
Luton Town
£10.2m
His rapid development has seen his value surpass that of striker Anthony Martial, who is now worth just £8.5m, eight years after his seismic £61.5m move from Monaco.
Given his tender age of just 21, the "unbelievable" defender, as dubbed by Statman Scouts, has huge potential to improve with his impressive season at Luton not going unnoticed.
He received an England U21 call-up for the current international break, with Mengi potentially featuring in their next game against Luxembourg tonight.
With the Red Devils' current injury problems at centre-back, they might live to regret selling Mengi when they did with the former United youngster starting to showcase his talents which were once hindered by injury.