Days after scoring a superb hat-trick to begin Barcelona’s Champions League campaign in style against Ajax, Lionel Messi is set to make his 250th La Liga appearance in Saturday’s trip to face Rayo Vallecano. In the previous 249 outings, since coming through Barcelona’s La Masia academy, he has scored an astonishing 221 goals.  

Messi remains the focal point of Barcelona’s play, but there has been much talk of a subtle shifting of the team’s famed tiki-taka style under Gerardo Martino. The Argentinian was forced to defend the side’s at-times more-direct approach in the win over Ajax. And ahead of this weekend’s encounter, assistant coach Jorge Pautasso, handling media duties with Martino absent to attend the funeral of his father, reiterated that what they are doing is about evolution not revolution.

“We’ll never take the style away,” he said, according to Barcelona’s official website. “We have come here to add to, not take away from, what Barca has done so well in recent years. If things go bad for a while and we drop back and regroup, that doesn’t mean we’re playing on the counter attack.”

Pautasso confirmed that Martino will return from Argentina in time to take charge of Barcelona at the Vallecas. Gerard Pique’s presence in Madrid is in doubt, however, as he battles a thigh problem. If the central defender is not passed fit, Pautasso confirmed that Marc Bartra would be the man to step in, with Carles Puyol still returning to full fitness. Jordi Alba remains on the sidelines.

It is in defense where Barcelona’s major problems still lie. In their last league outing, the champions let a two-goal lead slip in the final 10 minutes at home to Sevilla before some injury-time magic from Messi and a close-range finish from Alexis Sanchez rescued the three points.

Still, Barcelona’s concerns pail into significance compared with those of their next opponents. After winning their opening match of the season, Rayo have now lost three matches on the bounce by a combined score of 12-1. With Barcelona having won 7-0 and 5-0 on their last two visits to Vallecas, Rayo head into the fixture as massive underdogs. Mexican forward Nery Castillo and midfielder Iago Falque -- on loan from Tottenham -- have returned to training for Paco Jemez’s side.

Rayo Vallecano (probable)

G: Martinez

D: Tito, Galeano, Galvez, Nacho

M: Trashorras, Niguez

Perea, Bueno, Falque

F: Larrivey

Barcelona (probable)

G: Valdes

D: Daniel Alves, Pique, Mascherano, Adriano

M: Xavi, Busquets, Iniesta

F: Pedro, Messi, Neymar

Prediction: Barcelona’s slight shift in style remains a work in progress, but should ultimately prove beneficial. Rayo tend to play with a positive outlook and Barcelona’s adaptation to occasionally sit deep before hitting teams on the break could reap dividends. A victory as emphatic as Barcelona have produced in the past two seasons at Vallecas is not out of the question and it is hard to see anything other than a comfortable away win.

Rayo Vallecano 1-4 Barcelona

Where to watch: The Primera Division match will kick-off at 2 p.m. ET. Coverage will be provided by beIN Sport, with a live stream available on beIN Sport TV.