It was never meant to be like this. Leicester City should be cannon-fodder at Old Trafford in May, extras on the main stage as Manchester United play a starring role. It is hard not to be excited about Claudio Ranieri’s team winning the title at the self-styled Theatre of Dreams, but the subplot on Sunday between these sides is likely to have more far-reaching consequences.

Arsenal’s faltering end to the season and Manchester City’s patchy form have given Louis van Gaal’s team a sniff of the top four. United are five points behind both teams with a game in hand. Suddenly, the battle for the top four is on again.

Arsene Wenger’s side look more vulnerable than City. Their tame end to the season — three draws in the past four games — suggest they have lost some of their focus. They have to go to the Etihad next week and the mood in north London is increasingly toxic. Wenger has thrashed around for answers and looked desperately for culprits to blame for his side’s failings. The problems are closer to home, though. “Wenger is the most insightful man in football,” one of his friends likes to say. “Except about Arsenal.”

Wenger, 66, is stubborn. He defends his methods in the strongest of terms and has used Arsenal’s run of 18 successive Champions League qualifications to deflect criticism away from suggestions that the Gunners are underachieving. If Wenger’s team do not extend that run of involvement in Europe’s premier tournament, it would undermine the Arsenal manager’s entire ethos.

Wenger has been able to find reasons why Arsenal have failed to win the title since 2004 — the cost of building the Emirates, Chelsea and City’s massive wealth — but the institutionalized excuse-making looks increasingly bankrupt of ideas. The Frenchman has turned full circle, blaming the stadium. This time it is the atmosphere within it and the response of fans on matchdays rather than its financial impact. Yet Wenger is a very astute man. He knows what the problems are at Arsenal. His unwillingness or inability to address them leaves those who are close to him bewildered.

The team’s spine is questionable in both a physical and philosophical sense. Olivier Giroud does not lead the line with any conviction, it is hard to pick out a central midfielder who dictates matches for Arsenal and the centre-backs are liable to be bullied by forwards with pace and power. Only Petr Cech in goal looks like the sort of player to build a team around.

Arsenal’s mental approach is questionable. Graeme Souness, the former Liverpool captain and TV analyst, referred to Arsenal as “a team of son-in-laws” — the sort of men you would want to marry your daughter but players who lack the mean streak and competitive edge of the likes of Jamie Vardy. There is an acceptance at the Emirates that finishing in the top four is enough. That mindset affects the players. There appeared to be no belief in the Arsenal squad that they would beat Barcelona in the Champions League knockout round. Likewise, there was no real conviction that a title challenge was on, even after they beat Leicester in February. Too many players are comfortable under the top four security blanket.

If that was taken away, where would it leave Arsenal? If they finish fifth, Wenger’s detractors assume the manager would leave. There is almost no chance of that. He is extremely strong-willed. Plus, he makes all the decisions at the Emirates. Wenger will leave the club when he decides and on his own terms. It is inconceivable that he would be sacked.

It would, however, force Stan Kroenke, the club’s major shareholder, to consider his options. One of the worries for Arsenal fans is that too much power is centred on Wenger and there has been little thought to what might happened when he eventually decides to step down. Finishing outside the top four would be the beginning of the end for Wenger.

A victory for Leicester on Sunday at Old Trafford would provide a satisfying end to one of the most unlikely stories in English football. If United take the three points, though, it offers up the possibility of creating a seismic change in the Premier League. The top four without Arsenal is unthinkable. Arsenal without Wenger is unthinkable. If United can overtake the London club, those two notions might begin to change.

Delle Alli learns hard lesson
Delle Alli and Tottenham Hotspur learned a severe lesson against West Bromwich Albion. The 20-year-old’s season is over after he was banned for a punch on Claudio Yacob. It will do him good.

One of the best things about Alli is his will to win and his refusal to be cowed by opponents. Sometimes, though, he is prone to lashing out. Aggression is good as long as it is focused. It needs to be channeled properly.

Spurs as a whole were a little too confident against West Brom. They were showing off before the game was won. Playing to entertain is fine as long as the points are in the bag. Otherwise you end up like Arsenal.