Only Madrid themselves had collected more points at home than the Basque club going into this game, making it one of the sternest tests they will face as they attempt to seal a 33rd Spanish championship.
They had to overcome some adversity to come through it unscathed. Here's how the action unfolded...
LA LIGA SCORES
|Athletic Club||1-2||Real Madrid|
|Deportivo La Coruna||Sun||Celta Vigo|
Karim Benzema and Casemiro got the goals that sealed Madrid's win at San Mames, which was only the second defeat Athletic have suffered on home turf all season in La Liga. The other came back in August against Barcelona.
Casemiro was instrumental. After playing a fine long ball to release Cristiano Ronaldo, who then set up Benzema's opener, the Brazilian pounced on Athletic's failure to deal with a corner to tuck home their second three minutes after Aritz Aduriz had netted an equaliser.
Surprisingly, three clubs battling to book a spot in the Europa League - or even challenge for fourth place - all suffered defeat. In addition to Athletic's loss, Real Sociedad were beaten away to Alaves and Las Palmas saw off Villarreal on Friday night. Just behind them, however, Eibar and Espanyol failed to capitalise in a 1-1 draw.
LA LIGA TABLE
|15||Deportivo La Coruña||27||6||9||12||31||42||-11||27|
Real Madrid are now five points clear at the top of the table, and though Barcelona can close the gap on Sunday they will have played a game more than Zinedine Zidane's men.
Otherwise, it's pretty much as you were. Valencia and Celta Vigo will have the chance to rise back above Real Betis and Las Palmas, who have at least temporarily overtaken them.
RONALDO TURNS PROVIDER
It has been two years and four months since Cristiano Ronaldo last provided two assists in an away game in La Liga, which he did here to help Real Madrid to a vital win over Athletic Club.
The Portuguese has remained prolific this season, scoring 19 goals in 22 league games, but the way in which Zidane has brought youth into his first-team squad to create more depth and decrease the emphasis on his stars has undoubtedly been to Madrid's benefit. If anything, it is now Barcelona - famed for their academy and playing philosophy under Pep Guardiola - who now seem to be more reliant on the individual talent of their 'MSN' forward trio for success.
Barca have scored more goals than Madrid but they have also had more off-days. Their potentially costly defeat to Deportivo La Coruna last weekend, probably a result of the euphoria of their incredible victory over Paris Saint-Germain in the Champions League, was yet more evidence of how they are being bettered for consistency by their biggest rivals.
ALSO OF NOTE...
It was a good Saturday for Atletico Madrid, who go into Sunday's match against Sevilla with less pressure on their shoulders due to the inability of Athletic, Villarreal and Real Sociedad to win. A win for Diego Simeone's men at the Vicente Calderon and the Champions League spots could be all but decided.
At the other end of the table, there is plenty to play for on what promises to be a significant close to the weekend. Sporting Gijon's meeting with Granada and Leganes' clash with Malaga are both huge games in the relegation fight and, after Simeone vs Sampoli, Barca aim to keep their title hopes alive against Valencia.