Real Madrid coach Jose Mourinho conceded it was "practically impossible" for his side to now retain their Primera Division title on a night where runaway leaders Barcelona further strengthened their grip at the top of the standings.
Third-placed Madrid suffered a double blow this evening, first conceding an 88th-minute equaliser to be held 2-2 at home by struggling Espanyol and then later seeing Barcelona thrash Atletico Madrid 4-1 in the tap-of-the-table clash at the Nou Camp.
That Barca triumph, which included yet another brace from Lionel Messi, lifted Tito Vilanova's men nine points clear of nearest challengers Atletico and also left them 13 clear of champions Real.
Mourinho admitted that gap is now probably too much for his side to make up.
Speaking before Barcelona's win, Mourinho told reporters: "It's practically impossible. It's 10 points which could become 13. Thirteen points in December are a lot. We had eight last year and despite drawing two matches we maintained that distance."
"It's practically impossible" - Jose Mourinho
Barca's triumph over Atletico means they now have claimed a remarkable 46 points from a possible 48 this season while it also saw Messi win his much-anticipated 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.
Earlier, Barca's city rivals Espanyol gave Vilanova's men a big helping hand by drawing at 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.