Barcelona's bid to have the football federation's one-match ban on Xavi temporarily lifted pending an appeal has been rejected by the Spanish Committee for Sporting Discipline (CEDD), the club said in a statement on Friday.
The leaders were trying to overturn a yellow card Xavi picked up for protesting against a refereeing decision in last weekend's 3-2 win at Sevilla - his fifth in the current cycle.
Barca host Real Valladolid on Sunday and, with a one-point advantage over chasing Real Madrid, can clinch the title with a final-day victory.
Andres Iniesta could be Xavi's replacement as he is close to a return after a month and a half out injured. But caution is the word with the World Cup starting next month.
"I have been working with the team again for several days and personally I feel very good," the Spain international told a news conference. "Being logical (though) I think it's unlikely I'll be in the starting line-up."
Barca midfielder Seydou Keita also returned to full training on Friday after shaking off an Achilles problem.
Left-back Maxwell, ruled out for three weeks after tearing a muscle in his right leg at Sevilla, is the only player unavailable.
Real Madrid visit Malaga on Sunday and could be without playmaker Guti, who missed training on Friday. Raul and Pepe are still injured but Rafael van der Vaart and Kaka have recovered and should be available.
Relegation-threatened Malaga have not won in 10 matches.
Real goalkeeper Iker Casillas has backed coach Manuel Pellegrini amid widespread media speculation the Chilean will be replaced by Inter Milan's Jose Mourinho at the end of the season.
"We are a new team with a lot of changes ... but the important thing is we are on the right track," said the Spain captain.
"The problem at Real Madrid is they demand so much and they don't give you time but the long-term project is very positive. It's very coherent and we are with him (Pellegrini)."
Fourth-placed Sevilla travel to Almeria on Saturday needing a victory to secure Spain's last Champions League qualification place. Next Wednesday they take on Atletico Madrid in the King's Cup final.
"I hope things go well in these two games, which are both finals, so the Spain coach takes note of me," striker Alvaro Negredo said of his outside chances of making Vicente del Bosque's final 23-man squad for the World Cup.
Real Mallorca, one point back in fifth, are the only side who can overtake the Andalucians and they host Espanyol at the same time.
Sixth-placed Getafe could qualify for the Europa League on their own merits for the first time, having twice made it as King's Cup final losers, if they beat Atletico Madrid away on Saturday.
Atletico have just finished celebrating Wednesday's Europa
