Real Madrid's faltering title defence deteriorated further with a shock 1-0 defeat at Real Betis, leaving them eight points behind rivals Barcelona and having played a game more in La Liga.
Hammered 5-1 by local rivals Sevilla last weekend, Betis enjoyed a famous victory at home against Jose Mourinho's mighty side, as a lovely 17th-minute finish from Spain international Benat was enough to inflict a third defeat of the season on Madrid.
With Cristano Ronaldo extending his dry spell, the forward having now scored only once in his past six games, Madrid were unable to find their way past inspired goalkeeper Adrian a week after his disastrous derby performance against Sevilla, and suffered another damaging evening in their bid to retain their Spanish crown.
Not only are they languishing far behind Barca - who have dropped only two points all season and play Levante on Sunday - Madrid are also a full five points behind city rivals Atletico following what by their lofty standards has been an awful three months of league football.
Mourinho made one change from the side that drew 1-1 at Manchester City midweek as Mesut Ozil took up residence behind Karim Benzema in place of Luka Modric. The Germany star was influential in the early stages when a trademark counter from Madrid culminated with his neat pass to Ronaldo, who had a firm low effort deflected behind.
Ronaldo turned provider soon after when accelerating violently down the left wing and jinking inside his marker to find Sami Khedira with a square pass. The German took the shot first time and got under the ball, lifting it over the bar when he really should have hit the target.
But Madrid's intensity soon dipped, and when it did, Betis punished them. Angel Di Maria made a mess of a clearance and looped the ball into the feet of Benat. Spain's new midfield star held off Khedira all too easily and from 25 yards arrowed a brilliant shot into the far corner.
The lead was almost extended when Ruben Castro raced onto a through ball from Salva Sevilla and saw his firmly struck effort palmed away by Iker Casillas, as a somewhat uninspired Madrid found themselves outfought if not outplayed by Betis, who were roared on by a vociferous home support.
The champions needed to be more clinical in the final third, though one flowing move carved Betis open after 31 minutes. Ozil slipped the ball square to Di Maria and he teed himself up for a volley that was deflected over. Soon after, Benzema volleyed home from a Xabi Alonso free-kick but was judged to be offside.
As Betis tried to pack the midfield they looked to exploit any chances on the break and it required a fantastic piece of defending from Sergio Ramos to prevent the deadly Castro from making it 2-0 with four minutes remaining of the first half.
Mourinho removed Khedira and Ozil for Kaka and Modric during the break in the hope of provoking a much better performance from Madrid. However, Betis went close to a second on 57 minutes when Juan Carlos curled a free-kick just wide following a typically wild moment from Pepe as he earned a booking for leaping into Salvador Agra.
Madrid began to squeeze the home side though and only a fine intervention from Angel prevented Benzema from tapping in after Adrian had deflected a Ronaldo cross into his path. Adrian then dived full length to tip a lovely curling effort from Kaka round the post.
Betis had irregular chances themselves, though both Salva and Castro were lacking composure when presented with excellent opportunities. The former took a touch too many when a glorious floated free-kick from Benat was touched back to him, while the latter fired over from Jorge Molina's pass.
Adrian was then forced to make a fine save to deny Benzema as Madrid threatened from a corner, and as the visitors piled forward the unbeatable home goalkeeper, ably assisted by centre-backs Antonio Amaya and Jose Antonio Dorado, denied the champions time and again in a brilliant display.
Betis survived a late penalty shout when the ball stuck the arm of substitute Emmanuel Nosa, but held on to record a stunning victory. Madrid, meanwhile, must be wondering whether their title campaign has already suffered fatal damage.