Barcelona narrowly secured their first victory of the season in a late comeback against Cadiz last weekend and are now set to face an even more formidable challenge against the "Yellow Submarine" on Sunday.

Villarreal, spearheaded by Spain's national team player Gerard Moreno, will present a tougher examination for the reigning champions, who have experienced a sluggish start to the season.

In the opening week, Barcelona was held to a frustrating goalless draw by Getafe, and it was only in the dying moments that Pedri Gonzalez managed to break the deadlock against Cadiz.

However, the midfielder will be sidelined for the next month due to a thigh injury, which is a setback for Xavi Hernandez and his team as Pedri is a pivotal creative force.

Recent addition Ilkay Gundogan played a role in creating Pedri's goal and has been integrating effectively into the Barcelona setup. Additionally, the 16-year-old prodigy Lamine Yamal has also showcased promise. On the other hand, veteran striker Robert Lewandowski has encountered difficulties since the beginning of the season.

The 35-year-old Polish forward has yet to find the net and has appeared somewhat disconnected from the team, leading him to drop back in search of involvement in the gameplay.

"The one he touches will be in his correct place—players want to come deep, I understand, but you can't lose your position."

If Lewandowski is not at his best, it may put a lot of pressure on the shoulders of youngster Yamal, who filled in for the suspended Raphinha last weekend and impressed, although Ferran Torres, who netted the second goal against Cadiz, is also hoping to start.

"(Yamal) is very well prepared. He's very mature, despite his age," said Xavi last week.

"He's a player who can make the difference, and that's not easy at Barça as a 16-year-old. I think he's ready to help the team."

Villarreal are without explosive winger Yeremy Pino, who is recovering from injury, but Moreno and new signings Alexander Sorloth and Ben Brereton Diaz have the quality to trouble Barcelona's defence.

Barcelona are still aiming to sign a right-back and, with Ronald Araujo injured, used Frenkie de Jong as a makeshift centre-back against Cadiz.

League leaders Real Madrid play early, visiting Celta Vigo on Friday night.

The Galicians are celebrating their centenary this week and will be aiming to cause an upset.

However, with Madrid's new arrival Jude Bellingham starting brilliantly—scoring three goals and providing an assist in his first two games - Carlo Ancelotti's side are a daunting prospect.

Rayo Vallecano, who like Los Blancos boast a 100 percent record, welcomes Atletico Madrid on Monday in a capital derby clash, while the other "perfect" team, Valencia, hosts Osasuna.