Barcelona under Ronald Koeman have shown sporadic thrilling moments but still have the propensity for being underwhelming, as shown in the 1-0 defeat at Getafe last week.
And under Zinedine Zidane Real Madrid are amidst a crisis hastened by their not-wholly surprising 3-2 home defeat to Shakhtar Donetsk in the Champions League.
In the case of Los Blancos, they've performed well for roughly 90 fractured minutes across a season where results have arrived through luck rather than design. And in the last seven days, that has caught up with them.
Cadiz defeated them in Madrid for the first time in their history - and deservedly so - and combined with the Champions League loss Zidane is under pressure.
The fact that there were no fans for either match has eased the tension and kept Florentino Perez away from the nuclear option, but fans or not, it's a gigantic two matches for Zidane.
Borussia Monchengladbach in the Champions League next Tuesday will have serious ramifications for their chances to qualify with a group that also contains Inter.
And therefore Zidane would want any other match right now other than the Clasico. A difficult week is ramped up into season-defining territory despite the fact we've just begun. His team are dysfunctional, desperate for consistency, grappling for a formation that works and a starting XI with players in form.
The Frenchman has fiddled with a midfield diamond and his tried-and-tested 4-3-3, but isn't really getting much from either; Martin Odegaard's position as a long-term No. 10 has been curtailed by below-par performances and injury, while Isco currently looks like he'd rather be anywhere else. Vinicius Jr and Rodrygo are maddening in their varying form, while Eden Hazard is injured - again.
And all of this has placed more emphasis on the seasoned campaigners. Remove Karim Benzema, Luka Modric and Sergio Ramos from this team and they are eminently beatable by any opposition at the moment, and the latter's injury which could force him to miss the Clasico is another monumental headache for Zidane.
And yet, on the other side, while Koeman is making strides he hasn't discovered the most coherent blend as of yet. There are strides forward; the form of Pedri, Frenkie De Jong finding himself and Ansu Fati's blistering start to the season. But the balance isn't right yet and Lionel Messi is still a little below his best.
Barcelona are not a club in a comfortable position as Cules continue to move to force Josep Maria out of his presidency. Debt has spiralled, virtually nothing was spent in the summer and Messi remains unhappy with the direction of the club.
And with the hierarchy placing demands on the squad to accept a 30% pay cut, some players are in revolt and there is a lack of harmony in the dressing room over the issue.
All the while £100m player Antoine Griezmann looks increasingly like he has no place here, a great footballer in the wrong kit. Koeman has some serious selection decisions to make ahead of his first major test as coach.
And so all of this creates a match filled with dread for almost everyone associated with the game. It comes at a less-than-ideal time for both teams and they haven't been as vulnerable as this, as a duo, for over a decade. Their positions of dominance both domestically and in Europe are under serious threat.
