Chelsea and Manchester United face an uncertain season ahead of Sunday's clash

When Manchester United last visited Chelsea in the league a year ago, they were humiliated. Poor defending gave Pedro the chance to put Chelsea into the lead after just 30 seconds, and the goals kept coming. Mourinho’s United left 4-0 down, and chastened. He turned up looking for an argument, but in the end he ended up looking sillier than Antonio Conte’s hair.

October marked the end of title optimism for United, and was the moment that Conte alighted on his 3-4-3 formation. Chelsea didn’t look back and, with Eden Hazard reinvigorated and Diego Costa back to his infuriating best, they went on to secure the title. For United, things were much worse. The defence lacked the ability to properly concentrate, and Paul Pogba was not enough to shake his side out of their lethargic funk in attack.

There are only four points between United and Chelsea this year, at a similar stage of the season, but the changes are obvious. Chelsea have struggled to match the heights of last season, whereas United appear much more accomplished. It makes any kind of prediction for the game between the two at Stamford Bridge much harder.

Mourinho has improved his new side, but he has not changed. The games against Liverpool and Spurs showed that against the top sides in the league, he is happy to take a point and if three are gifted to him, then he will bring along a second bus to park in front of the first. Regardless of what has happened to the two sides over the course of the summer, this approach is unlikely to change.

This means that Romelu Lukaku could notch up a seventh consecutive game without a goal, having been denied the chance to take a penalty in midweek against Benfica. But Lukaku is part of a more impressive United forward line. Marcus Rashford and Anthony Martial rarely play together, but their presence along with Henrikh Mkhitaryan and Lukaku means they are much more direct and dangerous on the break this season. When Pogba was present, Mhkitaryan was a much more effective presence too, but there is one other player who has had a huge impact on United.

Nemanja Matic has added much to United. He has given them a physical presence that means, at full fitness, United are a physically intimidating presence. He has more tactical intelligence than yesterday’s man, Ander Herrera. Where Matic uses his head, Herrera uses his elbows. He has a calmness and experience that no other outfield defensive player possesses. The problems with United’s defence have barely changed, as Eric Bailly is inexperienced and often injured, and Victor Lindelof has a touch of the Pruniers, for now at least. This is now indisputably a Mourinho side, but it is also still a defence that uses Phil Jones.

Much has been written about Matic’s exit from Chelsea. But while United have benefitted enormously from his arrival, it is wrong to assume Conte was a fool to let him go. His two replacements, Danny Drinkwater and Tiemoue Bakayoko, can offer plenty. Drinkwater is clearly not a first choice member of the team, but his clever passing will be of use. Bakayoko showed at Monaco that he offers a different kind of defence to the slow-moving Matic, but it is effective nonetheless.

However, Chelsea have struggled as both these players arrived injured, and unsurprisingly have taken their time to adapt. Add to this N’Golo Kante’s injury – he could feature tomorrow – and it is no surprise that Chelsea are struggling with a fundamental change to their guts.

They have also changed their methods up front. They have Alvaro Morata, who is on his way to being a proven scorer in England after just a few months, but they have lost Costa. He had plenty of faults, and was a tedious presence for most defenders and supporters, but his grating nature gave Chelsea an aggression they no longer possess. United’s defence would probably prefer an afternoon against Morata than they would against Costa.

After substantial changes to Chelsea, and with the demands placed upon them by regular Champions League football, it is no surprise that they are taking a while to adjust. They showed dreadful defending against Roma, not for the first time this season. They are vulnerable, as most sides are, to the counter-attack, and United have the players to exploit that.

More worrying than the usual post-summer difficulties for Chelsea are two factors. Firstly, Conte showed little ability at Juventus to compete simultaneously in Europe and in the league. It may be a quirk that will be overcome, a problem with Conte’s high intensity approach, or it may be a fundamental tactical weakness – but it is too early to know. Secondly, it is yet another Chelsea boss falling out with his players.

If true, it would not be the first time that Chelsea players have turned against their boss. Mourinho left acrimoniously most recently, as have Andre Villas Boas and Luiz Felipe Scolari. The reputation Chelsea have is that players understand that managers can be removed swiftly if they play poorly enough. Whether this is really the case, it is nevertheless supported by constant rumours and inconsistent performances throughout the seasons.

It is too soon to know if Chelsea’s players really are giving up, and if Conte really is at odds with a squad he took to the title just a few months ago. However, there are worries at United. Mourinho has been goading his players and supporters, which tends to happen towards the end of his tenures. He is already making eyes at Paris Saint-Germain, though this is probably gamesmanship over contract negotiations rather than a serious crisis.

Chelsea take on United, but with so many changes over the summer and problems for both managers, it would be foolish to expect any outcome with certainty.