When Cadiz earned promotion to La Liga by finishing second in the Segunda Division last season, pretty much nobody cared. They hadn't been seen in the top flight since 2006 and were surely just going to be heading straight back down.
And yet here we are, 12 games into the season, and Cadiz are sitting pretty in fifth after beating both Real Madrid and Barcelona. Fans have had no choice but to take notice.
Let's take a look at everything you need to know about these new giant killers.
1. They've Always Struggled in the Top Flight
Before this season, Cadiz had spent just 11 years in Spain's top tier, and they've never managed to finish higher than 12th.
Ten of those seasons came between 1981 and 1993, but after being relegated, they didn't make it back to La Liga until 2005.
Cadiz couldn't survive in the top flight and were quickly sent packing. Things got even worse when they were relegated to the third tier in 2008, and they were still there as recently as 2016.
2. Alvaro Negredo Is Their Star Man
In search of the firepower needed to survive in La Liga, Cadiz went out and brought in a man with plenty of experience all over Europe, Alvaro Negredo.
The 35-year-old arrived on a free transfer from Dubai-based Al Nasr with a record of 111 goals in 264 La Liga appearances with Almeria, Sevilla and Valencia, and he's bagged three strikes in his opening nine games for Cadiz.
He's only on a one-year deal but will see his contract automatically extended if he continues to impress.
3. Who Are the Other Key Men?
What has made Cadiz so likeable this season is that their squad doesn't exactly feature much obvious top-tier quality.
Former Real Madrid youngster and Reading loanee Alex Fernandez pulls the strings in midfield, while summer signings Alvaro Gimenez and Choco Lozano have both impressed since making the move.
There aren't too many other standout names in the Cadiz squad, but one player who may ring a bell is 21-year-old winger Bobby Adekanye, who left Liverpool in 2019 and is currently on loan from Lazio.
4. They Play a Stubborn 4-4-2
Manager Alvaro Cervera is a versatile boss who is never afraid to adapt his tactics to counter the threat of a specific opponent, but his bread and butter is a 4-4-2.
They love to defend deep and overload the midfield in an attempt to recover possession, before countering with real electricity and causing problems for their opponents.
Cervera's side attacks down the wings, using overloads from the full-backs to get the ball into the box for Negredo, whose aerial prowess is perfect for the system.
5. They Love a Set Piece
For a team who thrive on crosses and long balls, it should come as no surprise to learn that they love free-kicks and corners.
Last season, 24% of their 50 league goals came from set-pieces, so it's not just something Cervera uses in the hope of securing a smash-and-grab win. He sees real opportunity from dead balls and ensures his side spend a lot of time developing new routines.
Centre-backs Fali and Juan Cala love attacking in the air, and adding Negredo has only boosted Cadiz's options.