Real Madrid blew a chance to ramp up the pressure on La Liga leaders Barcelona in the title race as they fell 2-1 at Villarreal in a disjointed display on Saturday.
Yeremy Pino and Gerard Moreno's strikes either side of Karim Benzema's penalty were enough to give the hosts a sixth consecutive victory across all competitions and dent the Spanish champions' bid to retain the trophy.
Madrid remain level on points with league leaders Barcelona, who face Atletico Madrid on Sunday, and this season the country's two giants seem destined to tussle over the title themselves.
Carlo Ancelotti's side caught up with Barcelona last weekend after Xavi's team drew with Espanyol in the Catalan derby, but Madrid have not started 2023 particularly well.
Madrid's slim Spanish Cup victory over fourth-tier opponents Cacereno was followed by this bruising wake-up call at the renovated and newly reopened Estadio de la Ceramica, their second league defeat.
Ancelotti selected a Madrid starting line-up without a Spanish player in it for the first time in the club's history, according to media reports in Spain.
Los Blancos have struggled away at Villarreal in recent years, with two wins in 11 visits, the last coming in 2017 when Cristiano Ronaldo, Gareth Bale and Alvaro Morata were on the scoresheet.
Quique Setien's side, building confidence after a tough start for the former Barcelona coach, comprehensively outplayed Madrid in the first half, albeit without the goal they craved.
Francis Coquelin hit the post with a wonderful flick from Alberto Moreno's cross, while Dani Parejo fired wide.
Gerard Moreno played in Yeremy Pino but Madrid goalkeeper Thibaut Courtois did brilliantly to thwart the Spanish winger as he attempted to dribble round him.
Alex Baena drilled one effort wide and curled another narrowly over as Villarreal carved open Madrid's sluggish defence at will.
Madrid, still suffering after the World Cup break, began to pry themselves towards the end of the first half.
Benzema chose poorly when racing through on goal with Vinicius in support, crashing into last man Raul Albiol instead of springing the Brazilian.
When the French forward then did tee up Vinicius, he was denied by veteran goalkeeper Pepe Reina, starting after Geronimo Rulli's move to Ajax.
- Pino power -
Villarreal began the second half with the same vigour and this time it did pay off, with the electric Pino slamming home from Moreno's pass.
Benzema immediately had a chance to equalise but dragged a shot inches wide of the far post after being slipped in by Vinicius.
The 2022 Ballon d'Or winner eventually levelled from the spot after the most marginal of handball decisions was given against Argentine World Cup winner Juan Foyth after an hour.
Villarreal were infuriated but just three minutes later were gifted a soft penalty themselves when David Alaba slipped and touched the ball with his hand.
Moreno sent Thibaut Courtois the wrong way to restore the hosts' lead and they clung to it tightly.
Rodrygo Goes fired wide as Madrid hunted for an equaliser before Vinicius sprinted through on goal but fired over the bar when he might have scored.
Madrid travel to Saudi Arabia next to take part in the Spanish Super Cup -- but first they face an anxious wait to see if Barcelona drop points in the capital.