Barcelona striker David Villa has a bruised ankle and missed training on Friday as the leaders prepare for Sunday's match at home to fifth-placed Athletic Bilbao.
The Spain international, who scored in Wednesday's 2-1 Champions League defeat at Arsenal, should return to training on Saturday, Barca said on their website.
The champions' lead at the top was cut to five points and their record 16-match winning run ended last weekend after they were held to a 1-1 draw at Sporting Gijon.
Second-placed Real Madrid won 1-0 at Espanyol despite having goalkeeper Iker Casillas dismissed in the second minute.
With 23 matches played, Barca have 62 points, Real have 57 and Valencia are 10 points back in third on 47.
Barca need a win this weekend to put the last two matches, their worst run in more than four months, behind them, Brazilian defender Maxwell told a news conference on Friday.
"It's vital to get the three points and forget what happened both in Gijon and in London," the left-back said.
"Before the return leg against Arsenal (on March 8) we want to get the 12 points up for grabs in the league, starting with the match on Sunday."
Real are returning to something approaching their best ahead of Saturday's game at home to promoted Levante, according to coach Jose Mourinho.
"We have had some difficult matches and in my opinion the team is getting back to its best form," the Portuguese told a news conference on Friday.
"I was quite pleased with the Espanyol game because the team showed a lot of discipline and the footballers played at the limit," he added. "This interests me for the important period we are about to start and during which everything is up for grabs."
Mourinho has left central defender Pepe and midfielders Sergio Canales, Esteban Granero and Pedro Leon out of the squad for the Levante game, while captain Casillas is suspended and will likely be replaced by Antonio Adan.
Valencia, who have won seven of their eight games this year, should be wary of Gijon after the Asturians claimed a point against Barca last weekend, forward Juan Mata said ahead of Saturday's clash at the Mestalla.
"We saw a strong Sporting against Barca, with an intense game marked by closing down and an effective counter-attack," the Spain international told a news conference.
Villarreal were leapfrogged by local rivals Valencia last weekend after they slipped to a second straight defeat, away to Deportivo La Coruna.
After Thursday's Europa League goalless draw at Napoli, they can get their bid for a place in Europe next season back on track with a win at home to bottom club Malaga on Sunday.
"All the points are vital because we want to qualify for next season's Champions League," coach Juan Carlos Garrido told a news conference after the last 32 first leg tie in Naples.
Malaga will be without January signing Julio Baptista after tests showed the Brazil forward had suffered knee ligament damage and he was ruled out for four to six weeks.
