When Arsenal humbled Leicester City 5-2 at the King Power Stadium last September, it was seen by most as an accurate reflection of the gulf between the two clubs. While Leicester, in fourth place going into the fixture, had made a strong start to the season, they would inevitably slide back to reality. Arsenal, having taken over fourth spot, were the ream with realistic title ambitions.

It’s fair to say the script hasn’t exactly been followed in the time between that meeting and Sunday’s rematch at the Emirates Stadium. Sure, Arsenal are right in the title mix in third place, but it is Leicester, not Chelsea, not Manchester City, not Manchester United not even fellow traditional big guns Liverpool, that lead the way.

Along the way there have been numerous occasions when, as against Arsenal, their bubble was supposed to burst. In the space of just over a month between late November and the New Year, Leicester played Manchester United, Chelsea, Everton, Liverpool and Manchester City. A team that had been bottom of the table for much of last season would surely be found out during that stretch.

Instead, Claudio Ranieri’s outfit emerged top of the table, level on points with Arsenal. Still, the fairy tale was finally expected to end during their current trio of fixtures, at home to Liverpool and away to Manchester City and Arsenal. Yet so far Leicester have only enhanced their position. While the big-hitters continue to stumble, the East Midlands club have excelled in beating Liverpool and then brushing aside the winners of two Premier League titles in the last four seasons, Manchester City, on their own turf. Their lead atop the Premier League is now five points, with just 13 games remaining.

Sunday presents yet another hurdle for Leicester to overcome, one where once again a defeat will be seen not just as a loss of three points but as evidence that the idea of them winning the title belongs in the realm of fantasy. The players, though, don’t seem too concerned.

“We’re just enjoying it aren’t we? We’re just enjoying the ride,” said Jamie Vardy, who leads the Premier League with 18 goals. “If you start thinking about it too much it’s going to affect you, it’s as simple as that. We’ll just continue to do exactly the same thing we’ve done all season.”

Leicester can certainly afford to enjoy it. With a 10-point advantage over fifth-placed Manchester United, a place in the Champions League already looks well within their grasp. Not winning the title would hardly be seen as a failure for a club that began the season with the sole ambition of remaining in the division for another campaign.

The same is not true at Arsenal. Having gone 12 years without winning the title, it is hard to think that Arsene Wenger’s side will ever get a better chance than this. With Chelsea have fallen off the map for a season, Manchester United in disarray and Manchester City unable to find any consistency thanks to a jarring lack of backbone, this really should be Arsenal’s year.

Yet Arsenal go into Sunday’s game behind not only Leicester, but also, on goal difference, their fierce local rivals Tottenham. Wenger has long lamented what he viewed as an inability and unwillingness to compete with Manchester City, United and Chelsea financially, but there would be nowhere to hide if Arsenal miss out on the championship to either of the sides currently above them.

There has been much talk, not least from Wenger himself, that this season it is a different Arsenal, one, boosted by the calming influence in goal of Petr Cech, that has the consistency, maturity, and grit to get over the line. Yet their tally of 48 points from 25 games is just three more than at the same stage last season and seven less than the year before. Anything less than lifting the trophy in May must be seen as a failure.

Thus there is huge pressure on Sunday’s match for the Gunners. A defeat and an eight-point gap would present a real challenge to overcome in the final 12 games. History provides plenty of encouragement that Arsenal can get the job done, having won their last eight home league matches against Leicester. Arsenal should need little reminding, though, that this is not only a Leicester side unlike any before but a Premier League season unlike any before.

Prediction: While Arsenal’s quality, and especially that of Alexis Sánchez  and Mesut Özil, was obvious in the first match between the sides, the contest was far from as one-sided as the scoreline suggests. Indeed, not only did Leicester take the lead but they hit the woodwork twice before Arsenal got off the mark.

In fact, the way that Leicester happily concede possession and then hit with lightning speed on the break is tailor-made to cause Arsenal problems. The absence of Francis Coquelin and Santi Cazorla in the center of midfield has made Arsenal far more open, with Aaron Ramsey always looking to get forward. While Coquelin could make his first Premier League start since November on Sunday, Arsenal could still be exposed. But they also have the ability going forward to trouble Leicester’s defense. An entertaining share of the points could be in the cards.

Predicted score: Arsenal 2-2 Leicester City