Carlo Ancelotti's side drew 1-1 away at Rayo Vallecano, re-opening the title race.
Without Jude Bellingham to call upon due to injury, it was up to Joselu to open the scoring in the third minute.
But after Raul de Tomas equalised from the spot in the 27th minute, Madrid failed to come up with the goods as they were frustrated by new coach Inigo Perez - Andoni Iraola's former assistant.
Struggling to break down Rayo late on, the home side then looked more like scoring with a number of counter attacks, and when one fizzled out, Dani Carvajal lost his temper at a shirt pull.
The vastly experienced right-back delivered an elbow to Kike Perez, earning him a second yellow card and Ancelotti a huge headache.
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Carvajal deepens Los Blancos' defensive crisis, with David Alaba and Eder Militao out with ACL injuries.
Antonio Rudiger is also out of action, and issues are further complicated with Eduardo Camavinga picking up a yellow, which sees him also miss the next game against Sevilla.
Madrid's closest title rivals, Girona, play on Monday, and could close the gap to three points with a victory against Athletic Bilbao.
Real Madrid's injury-list isn't just extensive, but severe too, with Thibaut Courtois making it three ACL injuries for the season.
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Bellingham has already spent time out with a dislocated shoulder, but has now suffered a high-grade sprain in his left ankle.
The 20-year-old is likely to be out for a number of weeks, and already missed a Champions League last 16 1-0 win over Leipzig.
As Madrid's top scorer, the loss could be substantial as Ancelotti's side look to win both LaLiga and the Champions League.