Real Madrid effectively handed the Primera Liga title to Valencia when they slumped to their third defeat in a row, a 3-2 loss at home to lowly Real Mallorca on Saturday.
The defeat means that Valencia require two points from their remaining three matches to clinch their second league title in three seasons.
Rafa Benitez's side, who reached the UEFA Cup final earlier this week, could celebrate the title well ahead of time if they win their tricky away match at Sevilla on Sunday.
Valencia lead the table on 74 points, Real follow on 70 and Barcelona, whose 17-match unbeaten run came to an end earlier on Saturday when they lost 1-0 at relegation-threatened Celta Vigo, are third on 69.
Real fell victim to an inspired performance by a former player -- still part owned by the club -- Samuel Eto'o, who scored two brilliant solo goals to help his side to a 3-1 lead at the break.
Although Luis Figo pulled a goal back from the penalty spot five minutes after the restart it could not save them from a humiliating home defeat, their fourth loss in five league games.
For Mallorca the win will almost certainly ensure they remain in the top flight as they are now eight points clear of the relegation zone with most of their rivals still having three games to play.
Earlier, Barcelona were dealt their first defeat in 18 matches when they went down 1-0 loss at struggling Celta Vigo, Brazilian midfielder Edu scoring the winner when he curled a low shot inside the post from the edge of the area two minutes before the break.
The win lifted Celta out of the relegation zone but with all their immediate rivals still to play they could end up back in trouble before the weekend is out.
DREADFUL START
Real got off to a dreadful start when recently crowned African Player of the Year Eto'o put the islanders ahead in the 11th minute.
The Cameroon international raced on to a lofted through-ball, outpaced the Real defence, fended off centre-back Raul Bravo and then dinked the ball over Iker Casillas and into the net.
Real hit back almost immediately when centre-back Francisco Pavon got ahead of the Mallorca defence to head in a David Beckham corner in the 16th minute.
But it did little to disguise their problems controlling the Mallorca attack.
The Real back four panicked every time Eto'o got the ball and it was little surprise when he grabbed his second nine minutes before the break.
Picking up the ball 10 metres inside the Real half, he left Figo in his wake, jinked inside Bravo and Pavon and coolly slotted past Casillas to make it 2-1.
Mallorca went further ahead just before halftime when Alejandro Campano fooled Casillas with a well-rehearsed free kick.
Real were handed a lifeline six minutes into the second half when referee Eduardo Iturralde Gonzalez awarded them a penalty for a push on Figo and the Portuguese international converted.
Leading scorer Ronaldo had a goal disallowed after 65 minutes after he had controlled the ball with his hand but Real rarely threatened against a team who have the second-worst defensive record in the league.