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Rayo Vallecano enters the weekend riding a three-game skid in La Liga action, a poor run that looks set to continue on Saturday when the club welcomes Barcelona to Campo de Futbol de Vallecas.

Rayo made a promising start the season by claiming a 3-0 victory over Elche, but it has been all downhill since as the club dropped its next three contests by a combined score of 12-1.

Barcelona's fortunes are at the other end of the spectrum as the reigning Spanish champions have started their title defense in style, claiming maximum points from their first four league contests.

Most recently, Barcelona ran out at Camp Nou to a 4-0 victory over legendary Dutch side Ajax in Champions League play on Wednesday.

It was a vintage Barcelona display, but Dani Alves revealed to 'El Marcador,' a Spanish television program dedicated to covering the fabled club, that the Catalans are still tweaking their style of play under new manager Gerardo Martino.

"We are still in transition as we seek our best version and it's evidently not easy," said the Brazilian defender. "I think we're on the right track, and although we've made adjustments to the team, we're still winning.

"What we're doing is not so different, but we are introducing new things to counter certain teams that just come to defend and we're looking into ideas for creating more goalscoring chances."

Scoring was not an issue on Wednesday as Lionel Messi bagged a hat trick in the affair. The four-time Ballon d'Or winner is set to achieve yet another milestone as Saturday's clash with Rayo will mark his 250th La Liga appearance.

Messi's storied career at Barcelona has seen him make 212 starts and score a remarkable total of 221 goals.

And if Messi is considered to be the world's greatest player, Cristiano Ronaldo cannot be far behind. The Portuguese attacker netted a hat trick of his own in Champions League play this week to help Real Madrid to a 6-1 defeat of Galatasaray. On Sunday, Ronaldo will look to match what Messi achieves against Rayo when Real Madrid welcomes Getafe to the Bernabeu.

Also on Sunday, Valencia will hope snap a three-game slide when it hosts Sevilla at the Mestalla, Villarreal attempts to preserve its unbeaten start to the season when it heads to Estadio Balaidos to take on Celta Vigo and Real Betis looks to build upon its first win of the season when it hosts Granada at the Benito Villamarin.

On Saturday, Real Sociedad will look to bounce back from Champions League despair when it hosts Malaga at the Anoeta, Levante will test its three-game unbeaten run when it heads to the Estadio Mediterraneo to face Almeria and Atletico Madrid will attempt to stay perfect when it faces Valladolid at the Jose Zorrilla.

Monday's lone fixture pits Espanyol up against Athletic Bilbao at the Estadi Cornella-El Prat, and Friday's lone match saw Osasuna claim its first win of the season thanks to a 2-1 defeat of Elche.