They were the sixth-best side in the Spanish second tier last season. Now, heading to the New Year, La Liga's smallest club Rayo Vallecano are inside the top four ahead of Barcelona and Atletico Madrid, dreaming of the Champions League.
There is nothing special about the personnel they have. But their form in 2021-22 has been nothing short of astonishing, catching the eye of pundits and fans in Spain.
Their squad features Premier League flops such as Radamel Falcao and Bebe, both once on the books of Manchester United, Luca Zidane, the son of Zinedine, and former Manchester City trainee Jose Angel Pozo.
Under the guidance of promising coach Andoni Iraola, the Madrid-based outfit are making huge strides towards securing European football for next season — and maybe even a Champions League spot against all odds.
The results speak for themselves. After beginning the season with back-to-back defeats, Rayo went unbeaten in September and inflicted a shock 1-0 defeat on Barcelona, in which Falcao scored the winner, to end Ronald Koeman's reign at Camp Nou.
Since Iraola took charge in July 2020, the club's turnaround has been mesmeric. Last season, they finished sixth in the Segunda, qualifying for the play-offs by the skin of their teeth and beating Girona 3-2 on aggregate to secure their passage back into the top flight.
The 39-year-old began his coaching career with AEK Larnaca in Cyprus before taking over at Spanish second-tier outfit Mirandes and then Rayo. His high-energy style of play reflects the modern view coaches have on football, prioritising style over substance.
"I prefer too much chaos to too much organisation," he said.
"I prefer us to play at a high pace, even if it means a touch of precipitation, than play at a lower pace and have a bit more control. It suits us.
"We have to do our bit for the people to enjoy it."
After 18 matches this season, they are the most successful side at home in Europe's top five leagues, taking 25 points from a maximum of 27. That record trumps the richest teams in Europe, such as Manchester City, Bayern Munich and Paris Saint-Germain, for good measure.
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With that in mind, football fans might be eager to book up tickets to visit Rayo when coronavirus measures ease off. But if you walk down Avenida de la Albufera in Madrid looking for their stadium, you might just miss it.
On first glance, what you see towering in front of you appears to be a multi-storey car park. But the rough and run-down concrete exterior actually belongs to the Estadio de Vallecas, home of Rayo and located in one of the poorer neighbourhoods of the Spanish capital.
This is a club where business is conducted the old fashioned way. Matchday tickets can be purchased from tiny holes in the walls but not online.
A La Liga fixture against Levante, for example, can cost as little as €10 (£8) on the day the fixture is being played. Considering the football Iraola's men are playing at present, a ticket at that low price can only be described as a steal.
The ground itself only has three stands and holds a capacity of just over 15,500 seats. And yet, the fans pour in week after week, bellowing out songs of support and protest towards La Liga president Javier Tebas and their controversial owner, Raul Martin Presa.
What cannot be ignored is that Rayo have the lowest budget in the Primera Division and that is no surprise. The club were in the third tier of Spanish football only 13 years ago and have not received much in the way of investment since.
As reported by The Guardian, the situation is so bleak at the club that their women's team have been left without a doctor, while opposition medics have been forced to treat their players due to shortages. The owner, Presa, is constantly hounded by the fiercely loyal Rayo socios with chants of "vete ya" - which translates to "go away".
And yet, they are embarking on a historic journey. The club have only ventured into European competition once, via UEFA's Fair Play rule, in 2000-01. Their highest finish in La Liga came in 2012-13, when they finished eighth under the ultra-progressive coach Paco Jemez.
Inevitable comparisons have been drawn with how Leicester achieved the unthinkable by winning the Premier League in 2015-16, just 12 months after narrowly avoiding relegation.
While that does not appear likely for Rayo, who are 13 points behind Real Madrid, qualifying for the Champions League would represent one of the biggest overachievements in Spanish football history.
Because it is not just about finishing above Barcelona and Atletico Madrid, two superpowers in La Liga. There are Sevilla, Real Betis, Real Sociedad, Valencia, Athletic Bilbao and Villarreal, all clubs who regularly make their way into continental competition.
Even Bilbao, who recruit Basque players only, have a much larger budget available than Rayo. No one knows that better than Iraola, having spent his entire career with the club during his professional career.
The players are even starting to believe they can pull off a miracle, according to goalkeeper Stole Dimitrievski: "A few weeks ago, I posted a message saying: 'Dreaming of the Champions League.'"
"All my team-mates were laying into me, saying: 'Delete that.' And now we go for Christmas in a Champions League place and I'm laughing at them a bit."
The fact they are doing so with a 31-year-old Bebe amongst their ranks — the Portuguese winger discarded by Man United eight months after Sir Alex Ferguson's transfer gamble backfired — is remarkable.
Falcao, the veteran Colombian who managed just five goals in his two-year nightmare in England, has been revitalised at the age of 35. He has fired five in 10 LaLiga appearances this season alone.
Aided by the tireless work of linchpins such as Alvaro Garcia, Sergi Guardiola and Esteban Saveljich, Rayo have found a winning formula under their attack-minded visionary Iraola.
Their 2-0 win over Alaves last time out put them above Atletico Madrid, the reigning champions from last season who are struggling to rediscover their defensive expertise. Meanwhile, Barcelona were always going to falter without Lionel Messi this season, despite the best efforts of their exciting talents Pedri and Gavi.
If there was going to be a season where a team like Rayo could break the mould, it could be this one, although Iraola is not under any illusions.
"I'm convinced that this will turn and in the second half of the season you'll ask me the opposite," he said, when asked about his side's impressive form.
Still, that won't stop the players and fans from dreaming of the day in May 2022 when the smallest team in La Liga makes it to the world's biggest club competition.
To do so at the expense of Atleti or Barca would make it even sweeter.