It has been a busy week at Manchester United as the club have announced three first-team signings. The first was 22-year-old Andrey Santos from Chelsea, joining the club on a deal worth £48 million plus a further potential £2 million in add-ons. 

Then, United announced the signing of Karl Darlow, who will back up Senne Lammens in goal. The goalkeeper joined on a free transfer after leaving Leeds United this summer. 

Finally, in a shock move, United completed the signing of Youri Tielemans from Aston Villa this week. The transfer came out of nowhere and was completed within 48 hours.

The 29-year-old has signed a five-year contract with United and is set to join the team in the coming weeks, as he is now enjoying a rest period after playing a big part in Belgium's World Cup run.

With Manuel Ugarte sustaining an ACL injury during the tournament and Casemiro leaving the club, United were in need of a midfield overhaul this summer. Signing Santos and Tielemans is a good start, but the club are looking to add a third midfielder to accompany them and Kobbie Mainoo as midfield options for Michael Carrick. 

It is likely that United will target a deeper midfielder to fill the void Casemiro leaves and names such as Manu Kone, Alex Scott, Sander Berge and Carlos Baleba have been linked to the club.

It looked like United would target a marquee name to replace Casemiro in midfield, but so far they have not quite done that. They were interested in the likes of Elliot Anderson, Mateus Fernandes and Sandro Tonali, but these players have completed moves elsewhere for fees that United were not willing to pay.

The club had agreed a deal to sign Ederson from Italian side Atalanta, but that deal fell through. This was apparently due to concerns during the Brazilian's medical and the deal is now thought to be completely off.

According to the BBC, United are still looking to add a third midfielder to the squad this transfer window. It is unclear who that player will be as of now, but the club have a checklist they are looking for.

The BBC have said that this player will be experienced, capable of having an impact in the Champions League and will likely occupy a deeper role.

With Tielemans and Santos already arriving, United have three quality options in midfield, but none of them are a natural 'six'. The next signing will be a more defensive-minded player who can complement his midfield partner.

Many names have been linked to United over the summer already and there have been lots of midfielders on the move. United have missed out on some of their major targets, like Anderson, Fernandes and Aurelien Tchouameni but they have still made good signings.

Names like Manu Kone, Carlos Baleba and Alex Scott seem most likely at this moment in time but the club could surprise everyone like they did with the Tielemans signing. United have spent around £85 million so far this window so they could still bring in a big money signing to bolster their midfield. 

Aurelien Tchouameni would be most people's pick but it looks like he will stay at Real Madrid under former United boss Jose Mourinho. With the Frenchman no longer an option, the list of names begins to feel slightly underwhelming. Alex Scott would be expensive, which could cause United to look elsewhere, and he might not be the best fit as an out-and-out 'six'. 

Another name that has been mentioned is Adam Wharton. The Crystal Palace midfielder was left out of Thomas Tuchel's England squad for this summer's World Cup, which was seen as harsh after his outstanding performances for the Seagulls. He could be available for a move this summer and could be an interesting player for United to look at.

There were rumours that United would not look to sign Wharton due to him being a similar profile to Mainoo, but the pair have played at England together and share a good relationship. Wharton could be on the move this summer and United should consider the young Englishman.