Spanish football is in a state of shock as the 33rd round of matches in the BBVA Primera Liga approaches.

The 4-0 and 4-1 defeats suffered by FC Barcelona and Real Madrid in their respective Champions League semifinal first leg ties against Bayern Munich and Borussia Dortmund has left the two biggest clubs in the country reeling as they face the prospect of crashing out of the competition at the final hurdle.

The pace and power of the German sides left their Spanish rivals very much in evidence, but now the big two in Spain have to pick themselves up, brush themselves down and prepare for the return leg and attempt a miracle next week.

In the middle of that, however, is match-day 33 in La Liga and the fact the league title could be mathematically decided on Saturday night if Barcelona win away to Athletic Club Bilbao and Real Madrid lose away to neighbors, Atletico Madrid.

Both Barca and Real Madrid are likely to make wholesale changes for their weekend games with Leo Messi, who looked a long way off full fitness on Tuesday night, given the chance to recover, while others such as Andres Iniesta, Xavi Hernandez and Sergio Busquets make way for players such as Thiago Alcantara, David Villa, Alex Song and Christian Tello.

Athletic know a win would just about assure they are safe from any threat of relegation after a difficult season.

The away goal scored by Jose Mourinho's side in Dortmund gives them a better chance of a European fightback than Barca, but they still need something very special to progress in Europe. Mourinho will have to balance the fact that his side have to maintain local pride against a side they have not lost to since 1999 against the need to rest his best players for the European return leg.

Meanwhile Atletico will be able to call on striker Diego Costa, who had the yellow card he saw last weekend rescinded by the Spanish FA.

The other big game of the weekend is vital in the battle for fourth place and a spot in next season's Champions League as fourth placed Real Sociedad entertain Valencia. Real Sociedad's 5-2 win in Valencia earlier in the season saw Manolo Pellegrino sacked as Valencia coach and another win for Real Sociedad would see them open up a five-point lead over their rivals with five games remaining.

Meanwhile the battle to avoid relegation comes sharply into focus. Celta Vigo look to build on their last minute win at home to Zaragoza away to a Levante that has been very poor in recent matches, while Zaragoza, who are now bottom of the table have a vital game at home to third from bottom Mallorca.

A defeat for Zaragoza, who have not won in 2013, would almost certainly see coach Manolo Jimenez lose his job, while Granada coach, Lucas Alcaraz could find himself in a similar situation if his team lose away to Espanyol, who in the last 10 weeks have gone from being relegation candidates themselves to having a chance of playing in Europe last season.

Granada has taken just two points from nine games and are currently fourth from bottom, so a defeat would probably see them fall into the drop zone.

Other sides needing points are Osasuna, who play away to Rayo Vallecano on Sunday lunchtime and Deportivo la Coruna, who have a tough match away to Betis on Monday.

Elsewhere Sevilla travel to play Valladolid and Malaga are at home to Getafe looking to forget their 5-1 defeat to Valencia last weekend.