Barcelona will not risk calling up star forward Neymar for the potential title decider with Real Madrid, the Spanish champions said on Sunday, just hours before El Clasico.

The loss of the suspended Brazilian forward deals a big blow to Barcelona's hopes of denying their fierce rivals a first La Liga crown in five years.

Barcelona appealed to Spain's Court of Arbitration for Sport (TAD) late on Friday over Neymar's three-game ban in the hope it would be frozen, which would have allowed him to take part in the must-win showdown at the Santiago Bernabeu.

But with the pivotal clash looming -- kick-off is at 1845 GMT on Sunday -- Barcelona said they were abandoning their bid to have Neymar available.

"Given the legal uncertainty of the lack of a decision by the Court of Arbitration for Sport with the game tonight less than 12 hours away, and to focus all attention on the sporting aspect, the club has decided not to call up Neymar," an angry Barcelona statement said.

The Catalans said the TAD had created "a huge legal void".

Neymar is in the middle of a suspension for his red card and subsequent sarcastic applause of the officials in Barca's damaging 2-0 defeat to Malaga two weeks ago.

The club argue that until a ruling on the appeal is held, Neymar's ban should be suspended and therefore allow him to feature at the Bernabeu.

"As a coach I am prepared to play with Neymar or without him," manager Luis Enrique said on Saturday.

In the absence of a TAD ruling, Barca would have been taking an enormous risk by playing Neymar as they could have been sanctioned with a defeat for fielding an ineligible player. Enrique says his last Clasico -- he will leave Barcelona this summer -- is a must-win: Madrid hold a three-point lead at the top with a game in hand on their rivals.

"Given how close it is to the end of the season it is a decisive weekend," said Enrique.

"This time a Clasico can decide or almost decide the league or leave it very open. For us it is like a final, only a win will do."

Madrid could be boosted by the return of Gareth Bale from injury, but the fact the Welshman may not be risked is a further sign that Real have far more room for error.

Bale has been sidelined by an inflammation of the muscles around where he suffered ligament damage in his right ankle that kept him out for three months earlier in the season.

"He will be with us on Sunday," said Madrid boss Zinedine Zidane. 

"You will see tomorrow what team we are going to start with."

Should Bale not start, the on-form Isco is favourite to take his place, as he did for Madrid's thrilling 4-2 Champions League win over Bayern Munich after extra-time in midweek.

Centre-backs Raphael Varane and Pepe are Madrid's only injury absentees meaning Zidane is expected to name the same starting XI as against Bayern.

"There is a lot of tiredness, but also a lot of excitement and desire to keep doing what we are doing," added the Frenchman.

Only victory will salvage Barca's season after crashing out of the Champions League at the quarter-final stage to Juventus in midweek.

"For some it means it is a very attractive challenge and for others it means pressure," Enrique said. 

"I prefer to take it as an attractive and marvellous challenge. It's a chance to move level on points with Madrid."