Real fall further behind as Racing shock Bernabeu
"We have to try and stay calm," Real vice-president Emilio Butragueno told reporters after the match. "We didn't expect this and we will have to see if little by little we can recover, but it won't be easy."
Racing silenced the Bernabeu crowd when defender Ayoze Diaz scored with a curling free kick midway through the first half.
Real were still reeling when midfielder Felipe Melo doubled Racing's lead six minutes later, slicing through the home defence and stabbing the ball past Casillas.
Real were thrown a lifeline midway through the second half when Ronaldo cashed in on a defensive error by Racing's centre backs to nod home but they were unable to even salvage a point and they are now 11 points behind Barcelona.
Champions Barca have 40 points from 17 games, five ahead of second-placed Osasuna who will defend a 100 percent home record against Atletico Madrid tonight.
Villarreal are a further five points back in third spot after being held to a 0-0 draw at Malaga.
Real Betis hauled themselves off the bottom of the table with an emphatic 3-0 win at home to Alaves.
The Basque side have replaced them at the foot of the standings with 12 points from 17 games.
Real Zaragoza staged the fightback of the night when they came from two goals down at half-time to claim a 3-2 win at home to Athletic Bilbao.
In Italy, the Serie A table has a familiar look going into the Christmas break with the traditional big three of Italian football - Juventus, Inter Milan and AC Milan - occupying the top three places.
Juve, the reigning champions, will be feeling the most pleased with themselves over the holiday period with last night's 2-0 win over Siena ensuring they lead Inter by eight points and AC Milan by nine - Fabio Cannavaro and David Trezeguet got the goals.
Inter, meanwhile, shrugged off an injury to star striker Adriano to thrash Empoli 4-1.
The Brazilian hitman had already given Inter the lead before being taken off after a clash of heads with Andrea Raggi.
Julio Cruz made it 2-0 on the stroke of half-time and then, after Ighli Vannucchi had reduced arrears, Luis Figo and Obafemi Martins also got on the scoresheet for Inter.
Two goals from Alberto Gilardino and one from Andriy Shevchenko ensured Milan signed off for the year in style against Livorno, the surprise packages of 2005 who stay fifth.
Fiorentina beat Palermo 1-0, while elsewhere there were wins for Fiorentina, Parma, Ascoli and Udinese, while Lecce, who had Mirko Vucinic dismissed, were held 0-0 by Lazio and Messina drew 1-1 with Reggina.




