Jose Mourinho believes it is 'practically impossible' for his Real Madrid side to retain their Primera Liga title after Barcelona thrashed rivals Atletico Madrid 4-1.
Mourinho's side could only draw 2-2 against struggling Espanyol, leaving Tito Vilanova's men nine points clear of Atletico and 13 ahead of Real.
"It's practically impossible," said Mourinho.
"Thirteen points in December are a lot. We had eight last year and despite drawing two matches we maintained that distance."
Barca's triumph over Atletico means they now have claimed a remarkable 46 points from a possible 48 this season - and ensured Ballon d'Or nominee Lionel Messi won his much-anticipated on-pitch duel with Radamel Falcao.
Falcao put Atletico ahead in the first half with his 17th league goal of the campaign but, despite enjoying the better of the opening 45 minutes, Diego Simeone's side trailed at the break after a stunning goal from Adriano and a well-taken effort from Sergio Busquets.
Messi was a long way from his magical best but still ended up with two goals - his 89th and 90th of a remarkable 2012 - to quell Atletico's challenge in the second period.
Espanyol gave Vilanova's men a big helping hand by drawing at Real Madrid.
Mourinho's side fell behind to Sergio Garcia's 31st-minute opener but looked to have done enough to take the points after battling back to lead 2-1 through goals from Cristiano Ronaldo (45) and Fabio Coentrao (48).
However, Madrid could not finish off their opponents and paid a heavy price as Juan Albin netted a late equaliser that left Mourinho resigned to likely failure in their title defence.
Ernesto Valverde's winning start as Valencia coach came to an end as striker Alejandro Dominguez's late penalty against his former club earned Rayo Vallecano a surprise 1-0 victory at the Mestalla.
Valverde had guided his new side to three successive away victories - one in the Copa del Rey, one in the Primera Division and one in the Champions League - without them conceding a goal since replacing Mauricio Pellegrini earlier this month.
But that fine run - and his home debut - was ruined by Dominguez's 83rd-minute spot-kick as Valencia slipped to 11th in the standings.
Valencia's city rivals Levante, meanwhile, are fifth after Ruben Garcia's 19th-minute strike earned them a 1-0 win at Real Zaragoza.
Siena have sacked coach Serse Cosmi after their 4-1 defeat to Fiorentina last night.
The club confirmed Cosmi's departure on their official website in a short statement published at midnight.
"AC Siena has dismissed coach Serse Cosmi," the statement said. "The club would like to thank the coach and his staff for the work they have done in recent months with dedication and professionalism."
Fiorentina moved into the top five with a comfortable 4-1 win over local rivals Siena in a one-sided Tuscan derby.
Luca Toni and a David Pizarro penalty put Fiorentina ahead within 20 minutes, with Alberto Aquilani wrapping up victory on the stroke of half-time.
Reginaldo pulled a goal back for Siena, but Toni's second restored Fiorentina's three-goal advantage and took them to within two points of second-placed Inter Milan.
Siena ended the game with 10 men as Massimo Paci was shown a second yellow card, but Aquilani missed the resulting penalty.
It was a third straight Serie A defeat for the Siena, leaving them rooted to the foot of the table.
However, their record of four wins, five draws and eight defeats would be good for 15th place were it not for the six-point penalty they were given after the match-fixing scandal.
Former Sampdoria coach Giuseppe Iachini is now expected to be confirmed as Cosmi's successor.
Elsewhere Juventus extended their lead at the top of Serie A with a comfortable 3-0 victory over 10-man Atalanta.
Mirko Vucinic put Juve in front in the second minute with Andrea Pirlo and Claudio Marchisio adding further goals within the first 30 minutes.
Thomas Manfredini was then shown a red card for Atalanta, who were fortunate to avoid any further damage as Juve continued to attack but could not add to their first-half salvo.
Bologna pulled away from the relegation zone with an unexpected 3-2 win that dented high-flying Napoli's title hopes.
Despite going behind to Manolo Gabbiadini in the 10th minute, Napoli turned the game through Alessandro Gamberini and Edinson Cavani.
But two goals in three minutes from Panagiotis Kone and Daniele Portanova earned Stefano Pioli's side a shock win to leave Napoli eight points shy of Juve.
AC Milan claimed a fourth consecutive victory by downing struggling Pescara 4-1.
Antonio Nocerino found the back of the net inside 35 seconds and Elvis Abbruscato undid Pescara's promising defensive work with an own-goal.
Cristian Terlizzi briefly dragged the visitors back into the game but Jonathas headed into his own net in the final stages, leaving Italy striker Stefan El Shaarawy to rubber stamp the victory.
A late goal from Sergio Pellissier earned Chievo a 1-0 victory which denied Roma the chance to catch Fiorentina.
A draw seemed the most likely outcome at the Stadio Marc'Antonio Bentegodi, but Pellissier struck three minutes from time to ensure the points would stay in Verona.
Parma survived an early scare before three second-half goals ensured they would down Cagliari 4-1.
Roberto Donadoni's side recovered from going behind to Marco Sau's 20th-minute opener as Ishak Belfodil equalised one minute later and Jonathan Biabiany, a Jaime Valdes penalty and Belfodil's second goal late on kept Parma inside the top half.
Catania registered back-to-back league wins for the first time this season by coming from behind to beat Sampdoria 3-1.
Enzo Maresca converted an early penalty before Catania substitute Mario Paglialunga levelled after the break.
Gonzalo Bergessio boosted Rolando Maran's men into the lead with a close-range header and Catania made the points safe through Lucas Castro's effort on the stroke of full-time.
Andreas Granqvist earned Genoa a 1-1 draw against fellow strugglers Torino after Rolando Bianchi headed the opener.
Paris St Germain replaced Lyon at the top of the Ligue 1 table after downing their title rivals 1-0 at the Parc des Princes.
Blaise Matuidi's goal on the stroke of half-time decided the contest in favour of PSG as Lyon fell to only their third defeat of the campaign.
PSG's win sees them move above both Lyon and Marseille on goal difference, with all three clubs having accumulated 35 points from 18 games.
In-form Lorient powered to a fourth straight win - 2-0 against St Etienne - to continue their march up the table.
Jeremie Aliadiere and Alain Traore were on target in the first half as Lorient maintained their impressive run which began with victory over Toulouse and continued apace against Marseille and Sochaux.
Christian Gourcuff's men have not conceded a goal in that sequence and are now up to fourth having recovered superbly from a seven-game winless run earlier in the season.
Nancy remain at the foot after throwing away the lead to share the points in a 1-1 draw with 10-man Bordeaux.
Djamel Bakar fired the home side in front and their position improved further when Andre Biyogo Poko saw red at the end of the first half.
But Nancy were unable to capitalise and Henri Saivet secured a fourth successive draw for Les Girondins.
Nancy, who slipped to the bottom of the standing after a rare win for Troyes, remain seven points from safety.
Borussia Dortmund ensured they would head into the winter break third in the Bundesliga table following a 3-1 win at lowly Hoffenheim.
Mario Gotze's 26th-minute opener had been quickly cancelled out by Sven Schipplock (35) but second-half goals from Kevin Grosskreutz (58) and Robert Lewandowski (66) secured the points.
The defending champions, who still have a home DFB-Pokal tie against Hannover on Wednesday before heading into the month-long hiatus, are 12 points behind leaders Bayern Munich.
Hoffenheim will spend the second half of the season fighting for their top-flight status after today's defeat left them seven points from safety.
Nils Petersen struck an 88th-minute equaliser to earn Werder Bremen a 1-1 draw at home to Nurnberg.
The visitors took a shock lead through Timo Gebhart six minutes earlier but Petersen ensure it was not the match winner.
Ajax climbed into third place in the Eredivisie table after resisting a spirited challenge from Willem II to claim a 4-2 win.
Siem de Jong registered his seventh goal of the season in the 11th minute, with Danny Hoesen promptly doubling Ajax's lead three minutes later, and it looked like Frank de Boer's men had opened a clear route through to a sixth straight league win.
But Aurelien Joachim halved the deficit just two minutes after Hoesen's strike, with Genaro Snijders notching in the 28th minute to ensure the scores were level going into the break.
Ajax became more and more frantic as their hosts held them at bay throughout a frustrating second half, but Niklas Moisander gave De Boer's men the lead once again in the 72nd minute.
Willem came close to salvaging the late equaliser that would have kept Ajax in fourth place but visiting substitute Jody Lukoki squeezed in a final goal to confirm the Amsterdam club's ascent.
Ajax's victory curbed Feyenoord's own climb up the table after ADO Den Haag's Tjaronn Chery handed Ronald Koeman's men a 3-2 victory with his late own goal.
On-loan Parma striker Graziano Pelle made the most of Bruno Martins Indi's pass to score his 14th goal of the season with 15 minutes gone, but Den Haag levelled immediately.
Mike van Duinen was well-placed to turn home Chery's cross and the visitors looked good for parity going into the break, only for Pelle to push Kenneth Omeruo in the back, allowing Lex Immers to edge Feyenoord back in front from the spot.
A mad minute threw the game wide open when play resumed, Danny Holla converting a penalty when Martins Indi brought Van Duinen down in the area - an offence for which he saw a red card. Tom Beugelsdijk soon walked for elbowing an opponent and both sides were down to 10 men.
And four minutes from time it fell to Chery to hand Feyenoord all three points with a headed own-goal. Feyenoord remain in fifth place thanks to Ajax's success in Tilburg.
Sander Duits denied Vitesse Arnhem the chance to draw level on points with second-placed FC Twente - and keep Ajax at bay - as his stoppage-time goal earned RKC Waalwijk a point from a 2-2 draw.
Wilfried Bony put Vitesse ahead after just eight minutes at the GelreDome and it took Teddy Chevalier until the 78th minute to equalise for RKC.
The hosts were unfazed, though, and Simon Cziommer fired what appeared to be the winner nine minutes from time, only for Duits to earn RKC point three minutes into time added on.
Elsewhere, FC Utrecht opened a five-point gap over seventh-placed NEC Nijmegen as Leon de Kogel scored twice in a 3-1 victory over Heerenveen.
Both sides drew a blank in the first half but De Kogel seized on Jacob Mulenga's pass to put Utrecht ahead in the 66th minute. The 21-year-old striker completed his brace four minutes later before Alfred Finnbogason halved the deficit from the penalty spot.
But Heerenveen could not force an equaliser and Mulenga, who had previously had a goal ruled out for offside, made the hosts' points safe with his 89th-minute strike.
Follow us @SprtNationalUAE