Will David de Gea play? Can Daniel Sturridge make it? What about Anthony Martial? There's so many angles to Manchester United's clash with Liverpool - even before kickoff.
Avoiding the obvious, we take a look at five big situations well worth keeping your eye on this Saturday.
MEMPHIS DEPAY
Forget the denials, if Liverpool had their way, Memphis Depay would be in the away dressing room on Saturday. Negotiations were so well down the road that Depay visited Liverpool and met club officials as he prepared to leave PSV Eindhoven.
United were in the mix, but he looked nailed on to join the Reds. Then PSG came forward, news of a whistle-stop visit to Paris reached Louis van Gaal and in stepped United.
Brendan Rodgers denies Liverpool were ever in for Memphis. But without Van Gaal's intervention, the Dutchman - and not Roberto Firmino - would be lining up for the visitors.
Memphis is getting the better reviews so far this season. But if you forget the two games against a middling Club Brugge, neither player has turned in a decent Premier League performance. Both have arrived with big price-tags, but have been passengers so far. Can either player step up on Saturday?
DEJAN LOVREN
Dejan Lovren is a good player. Over three years with Lyon and last season with Southampton he proved that. Two clean sheets from the opening two games and it appeared he'd turned the corner. We'd now see the player for Liverpool, the leader, Lovren has been threatening to be.
But then came West Ham and that horror show. He's talked about putting the performance behind him. But on Saturday he faces a record-breaking Wayne Rooney, at the top of his game. And he's at Old Trafford. The Stretford End will be on top of him all game.
If Liverpool are to win at Old Trafford, they will need something immense from Lovren. He has it in him. But the Croatian needs to show - if only for himself - that he belongs on this stage.
NATHANIEL CLYNE vs LUKE SHAW
This match-up is an absolute beauty. Both former Southampton players. Both attacking fullbacks. Both England starters. And both squaring off directly against eachother in the biggest game there is.
For all the inconsistency United and Liverpool have battled with so far this season, one constant they've enjoyed has been the excellent form of Clyne and Shaw. This will be the first meeting of a rivalry that could last for a decade.
Can you split them? It's a struggle to see how. The one edge Clyne (perhaps) has on Shaw is that he does have a goal in him. But whatever happens on Saturday, we'll be witnessing the dawn of one of the great modern day Premier League duels.
DALEY BLIND
Will Brendan Rodgers target Daley Blind? Particularly if Christian Benteke is passed fit? The Dutchman was exposed at Swansea City a fortnight ago, with Bafetimbi Gomis proving far too powerful for the makeshift centre-half. It was the first time United's defence had come under consistent pressure - and they fell well short.
If Benteke plays, it will be up to Liverpool to help him isolate Blind one-on-one. He goes into the game having taken a battering from the Dutch press for his role in their demise against Turkey. Lovren may be Liverpool's big weakness, but as Gomis proved at the Liberty, Blind, as a centre-half, makes a decent midfielder.
BASTIAN SCHWEINSTEIGER
Basti versus Emre Can? How about that for a master versus apprentice match-up? Can is regarded as Schweinsteiger's heir apparent and Saturday will be a great barometer to see how close they are.
Schweinsteiger has had solid start to his United career, with preseason fitness issues blamed for a lack of mobility. But against a Liverpool shorn of Jordan Henderson and Adam Lallana, he really needs to boss the game.
These are the occasions he was brought to Old Trafford for. The world will be watching, including Pep Guardiola. It shouldn't be Morgan Schneiderlin holding things together, it should be the German.
Against Emre Can, will Basti prove to doubters - including his old Bayern Munich coach - that he still has plenty to offer on the biggest stage of all?
