The Basque derby isn't the fiercest, most competitive or most entertaining fixture in world football, but it's nonetheless a rivalry draped in unique traditions and, dare I say it, unity.
But like all derbies there have been some belting contests down the years, with the odd couple even having a direct impact in determining the victor of the La Liga title in the 1980s.
Here are the pick of the bunch...
Real Sociedad 5-0 Athletic Bilbao (1976)
Sure, Sociedad's 5-0 thrashing of their intra-city rivals was pretty historic, but it's what unfolded before kick-off which makes this clash so significant.
It was an all inspired by Sociedad's Josean de la Hoz Uranga - a squad player in José Antonio Irulegui's side and enthusiastic Basque nationalist - who wanted to speed up the process of re-legalising the flag of the Basque Country - the Ikurriña - after its prohibition under Francisco Franco's orders in 1939.
*note: Franco and the Basque region didn't exactly see eye-to-eye - putting it mildly.
Uranga, though, felt it was time to act and the Spaniard did just that, overcoming several obstacles just to get his hands on the bleeding thing and sneak it into the ground before ensuring both sets of players were in unanimous agreement about participating.
What followed was a watershed moment in Basque history, as La Real skipper Inaxio Kortabarria strode out alongside his Athletic counterpart José Ángel Iribar with the flag aloft before placing it on the centre circle for all those in attendance to gaze upon.
And it was all spearheaded by a player who wasn't even in the matchday squad, but Uranga's ploy nevertheless served as the catalyst for the re-legalisation of the Ikurriña in 1977.
Real Sociedad 2-1 Athletic Bilbao (1982)
No fixture has held more single-game significance in La Real's history than the Basque derby in April 1982.
Following decades of Los Leones superiority since the rivalry's inception in 1909, the turn of the 1980s signalled the start of a brief power shift in the Basque Country.
Inspired by the talent of Roberto Lopez Ufarte, Jesús María Satrústegui and Jesus Zamora, La Real would go on to secure their maiden La Liga crown in 1981 and would have a chance to go back-to-back a year later.
And how bloody good would it be to do it in front of your arch-rivals.
Heading into the final day of the campaign a point clear of Barcelona - it was still a two-point for a win system back then, by the way - La Real knew victory over their intra-city rivals at the Atotxa Stadium would see them crowned champions once more.
Goals from Ufarte and Zamora saw them race into a 2-0 lead before a late Manu Sarabia strike sent a wave a nausea through the home faithful's stomachs. La Real held on, however, to secure another title, sparking scenes of jubilation at the Atotxa.
Athletic Bilbao 2-1 Real Sociedad (1984)
The San Sebastian-based outfit's reign at the pinnacle of Spanish football didn't last long, mind, and to make things worse, they were usurped by Los Leones as the country's supreme force.
Athletic became Spain's team of the mid-80s as La Real slumped to mid-table obscurity.
And just like Sociedad did in 1982, Athletic would have the chance just two years later in '84 to secure back-to-back titles with victory over their local rivals on the final day.
With the San Mamés Stadium packed to the rafters, Los Leones took the look lead through the opportunistic Jesus Liceranzu before Lopez Ufarte looked poised to spoil the party with a headed finish at the back post.
The hosts seized the initiative once more, however, as Liceranzu - a defender who scored seven times that season - nodded home from a set-piece to gift Los Leones the title, pipping Real Madrid - as Sky Sports cricket commentator Ian Smith would cry - 'BY THE BAREST OF MARGINS!'
A single goal was the difference, if you're curious.
Real Sociedad 3-2 Athletic Bilbao (2004)
Sure, this might've been played out between two pretty average sides, but comebacks are bloody brilliant and even sweeter when it's ya local rivals on the end of a pendulum shift.
And in this November clash in the 2004/05 campaign, it was the visiting Athletic who found themselves 2-0 in front despite La Real's dominance in the opening exchanges. Individual brilliance from Santiago Ezquerro and a smart Ismael Urdaiz finish silenced the Anoeta before the break but they had little to fear; momentum in derbies is as prominent as it is in FIFA 20 Ultimate Team.
And 11 minutes after the restart La Real halved the deficit through Nihat Kahveci before the Turkish international bagged the equaliser five minutes later; poking the ball through the legs of substitute keeper Roberto Pampin.
With 17 minutes remaining, the inevitable happened; as Igor Gabilondo rose highest in the Athletic penalty area to meet a wonderful cross from the right before directing his header past a despairing Pampin into the far corner.
Never in doubt, eh?
Real Sociedad 3-3 Athletic Bilbao (2006)
Out of the 43 deadlocks between these two in major competitions, this clash from 2006 was undoubtedly the most spectacular.
And ironically, it came amid two pretty dismal campaigns for both sides - Athletic: 12th, their worst finish for a decade and Sociedad: 16th, their lowest finish since 1962.
But hey, this was a belter of a contest.
Nihat was at it again as he lifted La Real into a 2-0 lead before a youthful looking Aritz Aduriz headed - duh - the visitors back into it two minutes after the restart.
The Athletic icon restored parity 20 minutes later before Morten Skoubo immediately snatched back the lead for the hosts.
On this occasion, though, an Andoni Iraola finish at the back post spolied the Real faithful's celebration as the entertaining contest ended 3-3.