Michael Carrick is a modern-day Manchester United legend; an impressive achievement given the endless list of midfield maestros that have graced Old Trafford's hallowed turf in the Premier League era.
The 36-year-old passing supremo boasts a 12-year career with the Red Devils, appearing 463 times for the club in all competitions, chiming in with 24 goals.
With Captain Carrick's transformation from player to coach now set in stone, Jose Mourinho's men lose the passing ability of a man who has won the Premier League five times, alongside three League Cups, a Champions League, a Europa League, six community shields and a Club World Cup title.
Former Mourinho golden boy Fellaini is also set to depart after rejecting a new deal, leaving the outspoken Portuguese manager short on central midfield options; especially considering Paul Pogba, Juan Mata and Jesse Lingard all play their best football further up the field.
This leaves Nemanja Matić and Ander Herrera as Mourinho's only two real senior central midfield options come the end of the season, both of whom lack the ability to knit together attack and defence in Carrick's effective yet stylish brand of football.
If the 55-year-old Setúbal-born manager wishes to compete with noisy neighbours Manchester City for the title in the 2018/2019 campaign, Mourinho will undoubtedly have to spend big in the summer.
But, who should he buy?
A World Cup winner with his naive Germany, the 28-year-old has been heavily linked with a £30 million move to Old Trafford after it was reported that the Real Madrid metronome is open to a new challenge following a four-year stay at the Santiago Bernabéu.
Kroos, who has appeared for Los Blancos 116 times in all competitions, nearly joined the Manchester club in David Moyes' ill-fated spell as Old Trafford boss and would seem to be the natural replacement for Carrick's ball playing skills.
A linchpin of the Real Madrid side, though, it's unlikely that Manchester United would be able to acquire the services of the German without shelling out a hefty sum of money.
Alongside Matic, the Kenyan international could provide an extremely solid base for attackers Romelu Lukaku, Marcus Rashford, Anthony Martial to reak havoc on Premier League defences.
Manchester United will have to act fast though as rumours are already circulating around a rival bid in the region of £40 million from Jurgen Klopp's Liverpool.
And Tottenham will be keen to hold onto the 26-year-old Kenyan international, especially if Argentine manager Mauricio Pochettino remains in London next season.
The 26-year-old Italy international, born in Brazil, is expected to be pursued by a host of European giants due to his importance for Napoli in their Serie A title challenge this season.
The former Verona man has been crucial to Maurizio Sarri's Partenopei and their stylish style of play, often protecting the back four and showing off his silky playmaking talents from a deep-lying position.
A reported fee of £35 million would buy Mourinho a classy operator, who boasts both Coppa Italia and Supercoppa Italiana winners medals, entering his prime footballing years.
Jean Michael Seri
The £35 million-rated Nice star is a quality passer of the ball, so much so the 26-year-old attracted the attention of Catalan club Barcelona and Pep Guardiola's Manchester City last year.
Seri, born in Grand-Béréby, made it into the Ligue 1 Team of the Year for 2017 also picking the Prix Marc-Vivien Foé award for best African player playing Ligue 1 in the same year.
The 5ft 6in Ivory Coast international plays the game with a great deal of energy and intensity. However, according to reports in the British media, Seri has admitted to not enjoying competing in cold climates.
"Can he do it on a cold, rainy Tuesday night in Stoke?" Jose Mourinho will be hoping he can.
Lazio's 22-year-old Serbian midfielder, affectionately known as SMS, has been turning heads around Europe thanks to his performances in Serie A this season.
With his agent Mateja Kezman claiming that the youngster is generating 'huge' interest from elite clubs across the continent, Manchester United would have to battle with Real Madrid and PSG if they were to pick up his signature in the summer.
At well over six foot, though, Milinkovic-Savic is just the sort of player that Mourinho loves: powerful in the defensive phase, clinical in the attacking phase, the Serbian has scored nine goals and picked up three assists in Serie A so far this season.
In fact, Milinkovic-Savic offers a sort of Matic-Pogba hybrid that could be the solution to the Portuguese manager's headaches in recent months.
Which of these players do you think Jose Mourinho should sign? Let us know by commenting in the section below.