Gareth Bale saw a goal disallowed as Barcelona and Real Madrid played out a 0-0 draw at Camp Nou on Wednesday.
La Liga's top two went into the contest level on points this season and with 72 wins each from previous league meetings, and there was nothing to separate them in a tense clash in Catalonia.
The match was rearranged from October after the initial date became a security risk due to the prospect of Catalan independence protests, and there were fans inside and outside the stadium making their voices heard over one of Spain's most divisive issues.
The action on the pitch was a little less fraught, Bale's second-half strike - ruled out for offside - representing the closest either side came to breaking the deadlock.
MATCH HIGHLIGHTS | BARCELONA VS REAL MADRID, AS IT HAPPENED
Madrid controlled the early exchanges and only Gerard Pique's timely intervention on the line denied Casemiro an opening goal with a header.
Marc-Andre ter Stegen beat away another Casemiro effort after Madrid had penalty shouts waved away following a shirt pull on Raphael Varane, who had earlier squared up to Jordi Alba.
Thibaut Courtois went untested until the half-hour mark, when he palmed away a teasing Alba cross and the covering Sergio Ramos cleared Lionel Messi's rebound from in front of goal.
Alba had a golden chance to snatch the lead before half-time but could only side-foot wide of the right-hand post following a sublime lofted pass from Messi.
The second half proved more of an end-to-end affair, Bale rippling the side-netting and then seeing celebrations cut short when his tap-in was disallowed after a VAR review for an offside against Ferland Mendy.
A frustrated Messi made a mess of a chance just inside the box, failing to connect cleanly with the ball to sum up a clash surprisingly short on attacking quality.
What does it mean? La Liga leaders deadlocked in title battle
Barca and Madrid are now on 36 points each at the top of the table, five clear of third-place Sevilla, with just one game left in 2019.
There was little to split them in a cagey encounter – the first goalless El Clasico since 2002 – and the title race certainly looks likely to remain a tense one in the new year.
Lenglet a leading light
In a match where defences triumphed, Clement Lenglet was probably the best on the pitch, keeping Karim Benzema away from Ter Stegen's goal and building play well from the back.
An off-day at last for Messi
The Clasico's record goalscorer swiped at thin air with his only half-chance of the game and was otherwise unable to get Barca firing in attack, with Madrid keeping him firmly in check.
In the final round of league games before the mid-season break, Barca hosts Deportivo Alaves on Saturday and Madrid welcomes Athletic Bilbao on Sunday.