Harry Maguire, Jadon Sancho and Cristiano Ronaldo - Ralf Rangnick's problems to solve to save Manchester United's season

Now that Ralf Rangnick is in charge at Manchester United, he has around three weeks to quickly turn around the side ahead of any potential transfers this winter.

Already, Rangnick has suggested that there is little to be done in January. He explained that he believes the quality of the squad isn’t the fundamental problem, and there will be fewer players available in the next window who can easily improve the side.

Saying that makes some sense. He will know that United spend big in the summer and rarely in the winter, and their scattergun transfer policy means that rarely is anything simple. After all, the club had no serious plans to secure the purchase of Bruno Fernandes a couple of years ago, they were simply scrabbling around for an available big name after being surprised to miss out on Erling Haaland to Borussia Dortmund.

There is time for Rangnick to get to work on the training pitch before any transfers that may or may not be possible. From front to back, there is nowhere that would not benefit from some refinement, and in some places there is clear need for an overhaul.

Yet for all United’s problems, if they were to find form for the rest of the season then they could easily finish in the top four, with a sensible list of transfer options and a solid tactical base on which the next man can build.

After years of misdirection and mismanagement, the defence remains porous. There were some suggestions that Rangnick influenced the team selection against Arsenal, and that further illustrates the problem for the team. Luke Shaw has had brief moments of improvement at Old Trafford but remains far too bulky to be effective over 90 minutes, and is tactically still very weak. On the other flank, Aaron Wan-Bissaka is usually excellent in one-on-one situations, but his understanding of the game seems just as poor as Shaw’s. Bringing in Alex Telles and Diogo Dalot might offer more going forward and better tactical awareness, but they are hardly convincing full-backs.

In the middle, Harry Maguire is still regularly at fault, Victor Lindelof has never shown merit, Raphael Varane is injured, and Eric Bailly is unreliable. It is vital that Rangnick - who admitted United concede too many - tightens up at the back while adding attacking thrust to the wings.

That is complicated by United’s midfield. Fernandes contributed a goal and more in midweek, but has been off his game compared to his earlier performances since arriving from Sporting Lisbon. Paul Pogba has never really shown anything close to his international form at United but is still much better than any alternatives, so he has been able to grow complacent. That’s made worse by the knowledge he can soon walk away. Nemanja Matic, Fred and Scott McTominay may be willing, but for various reasons there are questions over whether they are able. The middle three don’t offer enough defensive protection to help the nervy backline, nor does it offer enough to any attacking from wide. It also fails to offer enough to those ahead of it, where there are also problems.

Much has been said about Cristiano Ronaldo’s compatibility with Rangnick’s demands for hard running, but the German made it clear he can tell the 36-year-old Portuguese international remains in excellent shape, and his goalscoring record dwarfs his peers both this season and before, so a compromise should be easy to find. The greater problems are around him.

Edinson Cavani is a worthy back-up, but he will be leaving at the end of the season if not sooner. In the medium and short term, Rangnick needs a successor, to add to Ronaldo’s options. Marcus Rashford has been out of sorts since his return from his shoulder surgery, and given the hassle he gets from the press, may need help refocusing on his profession. Mason Greenwood, too, has the ability but not the consistency. It would be cheaper and useful if United can retain proof that players can move from youth team to first team even these days, and so giving them new motivation would improve United right now, and in years to come.

Perhaps the greatest upside is offered by Jadon Sancho. After years of pursuit, he arrived in the summer and promptly ignored and under-utilised, just like Donny van de Beek.

There are players of serious talent there, ignored by a manager without any of his own. Rangnick might not think there is much on offer from the market, but there is plenty already in his squad if he has the coaching nous.