Arsenal host Manchester United on Sunday in one of the oddest late-stage fixtures we've ever seen between the two sides. Whereas normally we'd be looking at title implications for one or the other, both sides currently sit outside the top four, and time is quickly running out on their attempts to finish within the Champions League places.
Arsenal currently sit in sixth, six points behind fourth-placed Manchester City (with a game in hand), and they'll be desperate for a win. They have no other shot at making Champions League, so it's three points or nothing for the Gunners.
Manchester United are just a point behind City in fifth, but they're in a whole different situation from Arsenal. Their best chance to make it into Champions League lies by winning Europa League, and they've just picked up a huge 1-0 win away against Celta in the first leg of their semifinal to take one step closer to that goal. If they win two more games, they're in Champions League, and because of that, Mourinho may very well continue to place his priority on that tournament. Wholesale changes may come on Sunday.
What are the keys to this strange matchup between the two old rivals?
Manchester United's piecemeal defense
United have a raft of injuries, but there's nowhere they've been hit harder than in the back. Marcos Rojo and Luke Shaw are both guaranteed to miss out, while Phil Jones and Chris Smalling will probably miss the match as well. That means it's Eric Bailly vs. the world in the back.
Depending on how much Mourinho decides to rotate, Bailly might not even start, and he could go with the Under-23 team he's joked about using given all United's injuries. Either way, it's going to be a real mix and match job at the back for United.
Arsenal's own defensive issues
Arsene Wenger's team has had problems defending all year. Shkodran Mustafi's shown some flashes alongside Laurent Koscielny, but it's really been the Frenchman holding it down on his own this season. Anytime he hasn't been in the lineup Arsenal have struggled, and they've had their fair share of problems with him starting, too. Arsenal need a win against United to even have a prayer of making it back into the top four, and if they're going to get the three points they'll need to be sharp at the back. Will Wenger go with a back four or a back three? Will Hector Bellerin make it back into the team? There's much to think about.
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In the kids Mourinho trusts
If the reports are to be believed, Jose Mourinho may just be rotating his team pretty heavily for the match against Arsenal. He's got the return leg against Celta to look forward to, so that means the kids might come out to play. Mourinho's never been known for a willingness to blood youngsters, but with the injuries piling up and more important matches to look forward to, the children may get their chance under Father Mourinho. Who knows? Some of them might just prove they belong there.
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Will Mesut Ozil show up?
Perhaps no Arsenal player has shouldered the brunt of the Gunners' failings this season more than Mesut Ozil. His languid style and deadpan expression hasn't sat well with fans often, and when he disappears from games, the knives really come out. Arsenal's chances of finishing in the top four are between slim and none right now, but if they're going to finish this season out strong, they need Ozil to show up and show out. But will he?
Will Pogba start?
Paul Pogba returned to United's lineup against Celta, and he was fantastic. He ran the midfield, and made it clear just how important he is to this team. He might be one of the players to have a seat on the bench if Mourinho rotates, but there's a solid chance he'll be in the first eleven from the start. Midfield is where Arsenal have struggled mightily this year, and if Pogba's in the lineup, they don't really have a true answer for him.
Trust The Ox in the middle
It's been a rough season for Arsenal, but there are a few bright spots. Alexis Sanchez has clearly been their best player, but Alex Oxlade-Chamberlain hasn't been too far behind. The 23-year-old England international has been moved all over the pitch for Arsenal, but he's given his very best wherever. He's been a revelation through the center though, and it would behoove Wenger to use him where he's been best. Trust the Ox. Use him as a midfielder.