It's the one area where David Moyes can ill afford misfortune, but it's his midfield that has been hit with injuries.
However, as soon as Carrick left the treatment room, Phil Jones entered it.
Ahead of the 3-2 win over Hull, the Manchester Evening News reported the 21-year-old will miss the next two weeks with a knee injury.
Jones has been forced into midfield duty in Carrick's absence and has done well. He's even chipped in with a couple of goals—against Norwich in the Capital One Cup and Shakhtar Donetsk in the Champions League.
If Carrick was fit enough to play the final 12 minutes against Hull on Boxing Day, you would assume he is fit enough to start against Norwich on Saturday.
Darren Fletcher's first Premier League start for more than a year was a bonus, but it's too much to expect him to start two games in three days.
The injury to Jones also gives David Moyes a headache at right-back. Rafael limped off with a groin injury against Hull and is unlikely to feature at Carrow Road. Jones has played at right-back as well this season, but he's out, while Antonio Valencia is suspended after his late red card against Hull.
It leaves Moyes with Chris Smalling or Fabio as his only options, and it's likely to be Smalling who gets the nod.
The 24-year-old has started the last three games at centre-half and his place should be taken by Nemanja Vidic, who returned on the bench at Hull.
Moyes has decisions to make out wide as well.
Valencia is suspended and Nani is injured, which leaves Adnan Januzaj, Ashley Young and Shinji Kagawa fighting for two positions. Danny Welbeck could play there, as could Ryan Giggs, but Young is starting to find some form and should start on the left with Januzaj on the right.
Up front, Wayne Rooney picks himself and Welbeck is likely to continue as his partner. If Moyes uses Welbeck as a wide midfielder, there could be a rare Premier League start for Javier Hernandez.
United vs. Norwich (possible): De Gea; Smalling, Evra, Vidic, Evans; Carrick, Cleverley, Young, Januzaj; Welbeck, Rooney.