Given the high-profile struggles endured by Angel Di Maria, we have 20 questions on the record signings of Premier League clubs...
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Who should start in defence?
Despite achieving back-to-back Premier League clean sheets for the first time this season over the New Year, United's defence was under the spotlight again following the 2-2 draw with West Ham in the FA Cup. James Collins benefitted from some particularly poor marking to head home both of the Hammers' goals and Nemanja Vidic admitted after the game: "They scored from the second ball which we should look at again, and we are definitely a bit disappointed. It is something to talk about."
Sir Alex Ferguson will no doubt be keen to see the back of his team's shonky defending - the Reds currently have the worst 'goals against' record in the top half - and the manager has a big decision to make over who should start Sunday's clash against Liverpool. Vidic has been gradually eased back into the team since his recovery from a knee injury but, while the captain's partnership with Rio Ferdinand was previously considered United's best centre-back pairing, the improving Jonny Evans threatens to break up the duopoly.
With Luis Suarez in superb form at the moment, it's vital that Ferguson makes the right selection and considering the Uruguayan's acceleration the more mobile Evans may be given the nod. Vidic still appears to be rusty after his long lay-off and Ferdinand, who was rested against West Ham, will probably earn a recall.
Should Shinji Kagawa start?
Kagawa has appeared in each of United's last three matches after returning from a knee injury sustained in October and Ferguson's intention may have been to bring the playmaker up to speed before the Liverpool clash. Kagawa struggled to have a major impact before his lay-off, but the 23-year-old has shown glimpses of his talent and an excellent lofted pass to Ashley Young helped United open the scoring in the recent 2-0 win over West Brom.
Considering Rooney's absence, Ferguson may opt to play Kagawa behind Robin van Persie in attack, where the Japanese's guile could be crucial in breaking down a Liverpool defence that has kept clean sheets in three of the last four Premier League fixtures. Kagawa's inclusion would keep Lucas occupied in midfield, but given that he still lacks the fitness to play at his peak for 90 minutes, another option is to use him from the bench if United need more creativity in the second half. The summer signing from Borussia Dortmund will certainly play a part at some point in the match and it's a huge opportunity to make a name for himself after a slow start.
Will Sir Alex play Ryan Giggs and/or Paul Scholes?
United's evergreen duo have struggled to maintain their usual high standards this season and it would be detrimental to the team's chances against Liverpool if Ferguson opted to start both of them in midfield. However, there is a case for either Giggs - who was impressive on the left against Wigan and in a late cameo at West Ham - or Scholes to start as their experience of playing in this fixture could prove crucial.
Liverpool have not been at their best this season, but they dominated United for long spells at Anfield even after Jonjo Shelvey's dismissal and could test the league leaders again if they settle into their passing groove. By partnering Scholes with Michael Carrick, United would lose some of the mobility offered by Tom Cleverley, but rival their opponents in ability to retain possession. Cleverley is likely to start, though, following his recent performances and a better option may be to use Giggs on the left, where his discipline can aid the not-always-reliable Patrice Evra, who will face a tricky test against Raheem Sterling. One thing is for certain - Giggs should be kept far away from a central role, which he occupied at Anfield when United were overrun in a poor first half.
Will Ferguson make any special plans for Luis Suarez?
Cutting his hands off isn't option, but would spare the possibility of another tiresome debate stretching long into next week. Liverpool's deviant extraordinaire has been in superb form this season, slicing and dicing defences (poor Clint Hill) and grabbing 15 goals so far to stand one behind Van Persie in the top scorer's chart despite playing for a team way back in eighth.
Considering United's back-line has been rather porous this season, Suarez will expect to score on Sunday and the Uruguayan will certainly have chances, be it through the team's or his own making. Few opponents have managed to contain the 25-year-old and Ferguson must decide whether to make any special plans to try and stifle the forward.
It would be almost impossible to man-mark Suarez given his movement, but United could benefit from a midfielder assigned to track the striker when he drops deep to collect the ball from Steven Gerrard and run at the defence in the final third. Phil Jones possesses the mobility to carry out such a job, but perhaps lacks the discipline, while Cleverley may also be instructed to shadow Suarez when he looks to receive the ball. It's likely Ferguson will continue with his normal approach this season of simply trying to outscore the opposition rather than be overly concerned with United's defensive duties.
Who should start on the right wing?
Ferguson was perhaps experimenting for Sunday's game when he started Rafael on the right wing against West Ham, but the Brazilian, who has also played in central midfield before, looked unsure of his responsibilities and struggled to have any impact on the game. The manager will be concerned with the form of Antonio Valencia, though, with the Ecuador international appearing subdued in recent performances and some way from his imposing best.
One option for Ferguson is to start Young on the right (if he chooses to play Giggs on the left), while Kagawa could also occupy a wide role after playing there frequently for Borussia Dortmund. Valencia may be given another chance to prove himself, but he won't find it easy against Glen Johnson, who is enjoying an impressive season.
Matt Stanger - he's on the Twitter.