It last happened in the 2003-04 season.
After trailing Real Madrid for most of the year, Rafael Benitez's Valencia stormed five points clear of Barcelona to wrap up the La Liga title. Madrid dropped to fourth and were pipped by a Deportivo La Coruna side at the height of its powers.
An exceptional squad with Santiago Canizares, Ruben Baraja, Vicente and Pablo Aimar also went on to win the UEFA Cup for Valencia, indicating years of dominance were ready to begin at the Mestalla. Nearly a decade later, Valencia still waits for its next title. Rather worryingly, so does any club that doesn't possess the name Barcelona or Real Madrid.
Eight seasons have finished since Benitez outlined himself as one of the world's most attractive coaching prospects. Real Madrid have racked up three La Liga titles since then. Barcelona have accumulated five. In a couple of weeks' time, make that six. Such dominance forces one to beg the question: When will a team other than Barcelona or Real Madrid win La Liga?
Hell, when will a team other than these two finish runner-up?
Since Valencia's triumph, only one side has toppled Barcelona or Real Madrid in the league. A stunning '07-'08 campaign saw Villarreal finish second and 10 points clear of the Catalan giants. The likes of Nihat Kahveci, Giuseppi Rossi and a young Santi Cazorla helped the Valencian team to an excellent finish—just four years before the club was relegated.
A number of outfits have shown potential of challenging the top two. Sevilla were just five points behind Real Madrid and Barcelona at the '06-'07 season's conclusion that saw Madrid take the title on head-to-head performances.
Despite landing two UEFA Cup trophies between '06 and '08, Sevilla never had enough power to overcome the titans of Spanish football. Similarly, Atletico Madrid captured the Europa League in '09-'10 and '11-'12, but haven't been able to topple the pesky twosome at the top.
Malaga's cash-injection since June 2010 showed great promise. Prominent signings including Ruud van Nistelrooy, Santi Cazorla and Jeremy Toulalan highlighted the squad's potential for success. A fourth-place finish still saw Malaga some 42 points off Barcelona's 100-point total, but progress was there for all to see. Until, of course, major debts saw the club part ways with many key individuals.
Even Athletic Bilbao, a team that took the Europa League by storm in '11-'12, have failed to significantly challenge on the domestic front. With the confirmation that influential forward Fernando Llorente is set to join Juventus in June 2013, it seems that little spark of success is over (via The Guardian).
With these examples in mind, answering our original question becomes a lot trickier.
As Lionel Messi's statistical performance shows, he is an integral part of Barcelona's success. The same can be said for Cristiano Ronaldo, who also contributes in nearly half of Real Madrid's goals. With these two players dominating the world stage, is it even possible for another team to clinch the La Liga championship?
It looks unlikely. Even so, players including Radamel Falcao, Isco and Alvaro Negredo prove the next subset of teams have individual quality. Below them, Ruben Castro, Piti and many more suggest La Liga is full of match winners. Although most of these players can help jot up three points, it's only Falcao who will consistently prove to grab the win for his team.
The real daunting prospect is this: Both Barcelona and Real Madrid have made plenty of mistakes in the transfer market. High-profile signings including Alexis Sanchez, Cesc Fabregas, Kaka and Luka Modric have failed to make the impact expected. These mistakes—if you can really call them that—have barely registered due to the overall quality of each squad.
Prolonged success has not only strengthened Barcelona and Real Madrid as global brands. It has heralded an era of football that is defined by individual icons. Much like Diego Maradona and Pele, we have Lionel Messi and Cristiano Ronaldo. Next up, international superstar Neymar is likely to run out in one of the famous shirts (via The Daily Mail). If Neymar doesn't arrive, it could be Gareth Bale (via The Daily Mirror).
These storylines might seem farfetched at the moment, but they underline the notion that Barcelona and Real Madrid work on a different level compared to the rest of La Liga. They can afford to make bad moves without consequence. The FIFA Financial Fair Play Rules may curb outrageous spending (see: Kaka), but both clubs continue to grow financially.
Recent thrashings in the Champions League may have many gossiping about the fall of Spanish football in European terms. While this could prove to be true, it is extremely unlikely Barcelona and Real Madrid are going to slip up so heavily that another team wins La Liga in the near future.
Sure, a lesser side may nip into second, but a combination of individual brilliance, squad depth and vast financial resources suggests both teams will share the Spanish championship for years to come.
When will any other team win La Liga? At the current time, perhaps "will any other team win La Liga" is the more adequate question.
Do you believe a side other than Barcelona or Real Madrid will win La Liga in the near future? Let me know in the comments section below and be sure to follow me on Twitter right here: