Barcelona host Real Madrid at 19:00 GMT on Wednesday
More than seven weeks after they were supposed to meet, Barcelona and Real Madrid go head to head at the Nou Camp on Wednesday in a match that looks set to decide who leads La Liga at Christmas.
Both teams started the season poorly but have improved significantly over the past few weeks, and they go into the midweek showdown - which was postponed from 26 October because of independence protests in Barcelona - level on points at the top of the table.
Old hands like Lionel Messi, Luis Suarez, Gerard Pique, Karim Benzema, Toni Kroos and Sergio Ramos will be on display, but a new twist to the rivalry comes with expected first El Clasico starts for two dynamic midfielders whose personal battle could help define this fixture for years to come.
Here is how 22-year-old Dutchman Frenkie de Jong has joined Messi as one of the first names on the Barca teamsheet, and why 21-year-old Uruguayan Federico Valverde has subdued talk of Paul Pogba heading to Real.
'Born to play for Barcelona'
De Jong rose to prominence during Ajax's thrilling march to last season's Champions League semi-finals. That led to an almighty transfer race - which Barcelona won ahead of Manchester City and Paris St-Germain.
It has not taken long for De Jong to justify his £65m fee, with the Netherlands international starting 15 of 16 league games and spending more time on the pitch than any outfield player except centre-back Pique.
Andrea Orlandi, the former Barcelona, Swansea and Brighton midfielder who is now a pundit for La Liga TV, believes the main question facing manager Ernesto Valverde is not where De Jong should fit in, but how to accommodate others around him.
"There is no doubt he'll start El Clasico. It's Messi and De Jong, plus nine others," Orlandi told BBC Sport. "He's done even better than I expected and looks like he was born to play for Barcelona."
One of the key conclusions from Barca's collapse at Liverpool in last season's Champions League semi-finals - a nightmare that still hovers over them - was the urgent need for more pace and power in midfield to avoid being overrun by more agile opponents.
De Jong has been the man to provide it alongside the relatively slow and immobile Sergio Busquets, Ivan Rakitic and Arthur Melo.
"He's amazing on the ball and his passing accuracy is always over 90%," added Orlandi. "But even more important is he adds a physical element to Barca's midfield. He competes for a lot of balls.
"He's very important off the ball because he runs constantly, like Xavi did in the past. People often didn't realise that Xavi always covered more ground than anyone else, and now De Jong is bringing that quality back into the team, which is what they desperately needed."
Dynamic Valverde's breakthrough season
Athleticism, versatility and quality on the ball. Many of De Jong's attributes are also evident in Valverde, who is set to make his first Clasico start after breathing new life into Real Madrid's midfield this season.
Valverde came through the youth ranks at Uruguayan giants Penarol in his hometown of Montevideo, before being snapped up by Real in the summer of 2016.
Los Blancos boss Zinedine Zidane started to put faith in Valverde towards the end of 2018-19 and picked him in five of the final eight games, but in the past couple of months he has taken a giant step forward to leap ahead of 34 year-old Luka Modric in the pecking order.
Valverde is an old-fashioned, box-to-box midfielder who does everything well and without fuss.
"He always seems to know what he has to do and where he has to be," said Phil Kitromilides, the commentator for Real's in-house TV channel.
"He is relatively inexperienced, but he left his country as a teenager, came to the other side of the world and then had a season on loan at Deportivo, which was a real learning curve.
"He keeps it simple, has incredible energy and is really quick. He's young but he's had a good education and has an intelligent football brain."
There have been suggestions Zidane may take advantage of Valverde's physical capabilities and selfless attitude by employing him in a man-marking role on Messi on Wednesday. However, that would detract from another of his assets, and one area where he looks superior to De Jong: his ability to create and score goals.
Valverde has two goals and two assists in his 12 La Liga appearances this season, and Kitromilides added: "He's got that Toni Kroos-like ability to arrive at the right time on the edge of the area and strike the ball cleanly. I think we'll see a lot more goals from him."
Forcing a way into the Kroos-Modric-Casemiro axis - arguably the best midfield in the world over recent years - would not be easy for any player. But Valverde has been delivering everything Zidane hoped the signing of Pogba would bring, and talk of the Manchester United midfielder coming to the Bernabeu has cooled during the Uruguayan's breakthrough season.
- We have to believe El Clasico will go ahead - Zidane
Tactical conundrums on both sides
Zinedine Zidane's Real Madrid are second in the La Liga table on goal difference behind Ernesto Valverde's Barcelona
The question of exactly where De Jong and Valverde will be deployed is one of several unknowns which make this game tactically the most interesting Clasico for years.
Barcelona are likely to line up in their usual 4-3-3 formation, with Busquets flanked by De Jong on the left and Rakitic on the right.
But manager Valverde has occasionally dabbled with a 4-2-3-1, with De Jong alongside Rakitic, Arthur or Busquets, and three from Messi, Antoine Griezmann, Arturo Vidal and Ansu Fati behind centre-forward Suarez.
Valverde could also opt for a 4-4-2 and seek to control the game in the centre of the pitch by omitting Griezmann and bringing in an extra midfielder - probably Vidal for his disruptive energy.
There are also questions over what Real will do, with Zidane's selection complicated by the absence of the injured Eden Hazard - a certain starter if fit.
Like Barca, Real usually set up in a 4-3-3 and have two of Gareth Bale, Rodrygo and Vinicius Junior alongside the in-form Karim Benzema up front.
However, in the recent Champions League meeting with Paris St-Germain, Zidane reverted to a midfield diamond with the lesser-seen Isco at the tip. The players responded with an excellent display and that system could be deployed again on Wednesday.
Zidane has said he likes to regularly vary the formation to make it more difficult for opponents to prepare to play against them, and we can't rule out a surprise selection from either manager.
It would be even more surprising, though, if the names of De Jong and Valverde do not feature in the starting XIs.
Source: bbc.com