Real Madrid's Welsh forward Gareth Bale (right) controls a ball next to Real Madrid's Dominicans forward Mariano Diaz (left) during a training session at the club's training ground in Valdebebas in the outskirts of Madrid on Feb 29, 2020 on the eve of the Spanish League football match between Real Madrid and Barcelona. (JAVIER SORIANO / AFP)

MADRID - Real Madrid entertain FC Barcelona in the 'Clasico' at the Santiago Bernabeu Stadium on Sunday night in what promises to be a season defining game that could go a long way towards deciding this season's title winner in Spain.

Real Madrid go into the game after a recent dip in form that saw them lose 2-1 at home to Manchester City in the Champions League

Real Madrid go into the game after a recent dip in form that saw them lose 2-1 at home to Manchester City in the Champions League on Wednesday night, lose 1-0 away to last weekend and draw 2-2 at home to Celta Vigo the previous weekend.

Those results have allowed Barcelona to overtake them in the Liga Santander table and a win for Barca on Madrid's home turf would see Quique Setien's side open a four point gap at the top of the table.

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Real Madrid boss Zinedine Zidane will make some changes to the side that lost on Wednesday with Tony Kroos, who sat out Wednesday's defeat, likely to come into the side, while Marcelo has a chance of returning at left back.

Vinicius Jr will probably keep his place, while Isco should play an attacking midfield role with the main doubt being whether Fede Valverde or Luka Modric occupies the final midfield position.

Barcelona's players take part in a training session at the Joan Gamper training ground in Sant Joan Despi in the outskirts of Barcelona on Feb 29, 2020 on the eve of the Spanish League football match between Real Madrid and Barcelona. (PAU BARRENA / AFP)

Barcelona travel to the capital after a 1-1 draw in the Champions League away to Napoli and although Setien's side were unimpressive in that game, the result makes them clear favorites to progress to the quarterfinals.

Gerard Pique was back in full training with his teammates after limping out of Tuesday's game after twisting his ankle and will partner either Clement Lenglet or Samuel Umtiti in central defense.

Jordi Alba trained with the group on Friday after several weeks sidelined with a muscle injury, but probably won't be risked, meaning Junior Firpo will continue at left back. The former Betis player is probably the weakest link in a Barca defense that is also without Sergi Roberto.

READ MORE: Pique's ankle a concern for Barca ahead of Clasico

Setien will have to decide whether to stick with the four-man midfield he used in Naples, with Arturo Vidal, Frenkie de Jong, Ivan Rakitic and Sergio Busquets, or to bring either Ansu Fati or recent arrival Martin Braithwaite into a 4-3-3.

If he opts to play four in midfield, everything points to it being a tight game with chances at a premium, but never count out Leo Messi, who scored four goals against Eibar a week ago, who could well be decisive.