LONDON - The wealth of elite clubs and financial restrictions on upstarts were thought to be locking in the established order in English soccer and suppressing ambition.

Just gatecrashing the Premier League's top-four to gain access to Champions League riches seemed an impossible feat for aspirational sides.

But a kaleidoscope has shaken the world's richest football competition in a season, defying not only the bookmakers but logic as well.

After 25 games it still seems unfathomable to have to delve into the lower reaches of the standings to find Chelsea in 13th place from where the defending champions are struggling to rise.

But it is the continued presence of Leicester at the summit to be cherished. With predictable leaders in Spain, Germany and France, Leicester is reinforcing the Premier League's status as the world's most engrossing and competitive domestic competition.

Leicester responds to each prediction that its bubble will burst by producing results like Saturday: Stunning Manchester City 3-1 and sending the 2012 and 2014 champions sliding to fourth.

Leicester winning the top flight for the first time in May would be the greatest title triumph in English football history. The Foxes started the season as 5,000-1 title no-hopers but are now 7-4 favourites with some bookmakers.

"It's either this year or never," manager Claudio Ranieri has told his players.

Adding to the state of flux in England is Tottenham occupying second place five points behind Leicester — its highest position at this stage of the season for 31 years. Unlike Leicester, the north London club has been champion of England, though only in 1951 and 1961.

There has been a surprise champion before from the east Midlands. Nottingham Forest was promoted to the top flight and instantly won the 1978 title. But that was in an era when the disparities are not as vast as currently.

With a team that cost around $30 million, Leicester beat a Man City lineup on Saturday that cost more than 10 times that to assemble. Leicester generated around $150 million in revenue last season while City made more than $500 million.

The richest team in England is Manchester United. Despite vast spending on players and a 2014-15 turnover of around $580 million, United is fifth in the standings, a dozen points behind Leicester with 13 games to go.

At this stage last season Leicester was rock bottom. Only in April did Leicester start its rise out of the relegation zone, although manager Nigel Pearson was still fired and the less temperamental Ranieri was brought in.

The brains behind the moulding of the team is Steve Walsh, the head of recruitment and assistant manager, who unearthed gems like Jamie Vardy.

The striker was a 1-million-pound gamble when he was plucky from non-league obscurity in 2012. Vardy has proved to be a bargain buy with a league-leading 18 goals. Riyad Mahrez has shared the plaudits as the Algeria midfielder has unsettled defences with his searing pace while also contributing 14 league goals.

But it's an all-round team effort, exemplified by a Barcelona-esque slick passing sequence in the 2-0 win over Liverpool last week. The defensive midfield shield, Danny Drinkwater, and goalkeeper Kasper Schmeichel have been integral to Leicester conceding only twice in seven league games.

All-round energy and pace in the central England team has seen teams as mighty as Man City crumble.

"Everyone feels they are participating, so playing badly means betraying the others," Ranieri told Italian newspaper Corriere della Sera in a weekend interview.

"I never once had to tell someone off for being lazy."

Leicester's Thai owners were dismissed as foolish for hiring Ranieri in July. The Italian had been away from the Premier League for 11 years since being jettisoned by Chelsea to make way for Jose Mourinho. And he had been out of work for more than a year after being fired by Greece during a woeful start by a top-ranked team in the easiest-ever European Championship qualifying format.

But from being a figure of fun and favourite to be sacked this season, Ranieri is flavour of the month again.

How has he achieved it?

One of the first tasks for the manager known at Chelsea as the "Tinkerman" for his constant changes to the lineup was winning over wary Leicester players.

"I realized they were afraid of Italian tactical approaches," Ranieri recalled.

"So I told the players that I trusted them and would speak very little of tactics. It was important to me that they all ran hard."

Beat third-place Arsenal on Sunday and Leicester will be closer to handing Ranieri the most satisfying end to the season in May: Lifting the trophy at his former Chelsea home.

"I always tell my players to find the fire within themselves," Ranieri said. "A chance like this will never come round again. Seek that fire, don't be ashamed of it."

Who will be ashamed?

Illustrious clubs beaten to the trophy by a team on a comparatively minuscule budget. And pundits who tipped Leicester for the drop and Ranieri for the sack.