Yes, Villarreal is a club that cannot be underestimated and against Barcelona they showed a game that was good enough to match Barcelona's game.
Although Villarreal lost by conceding 4 goals, they also managed to get 3 goals.
This is one of the exciting matches and very fierce competition for the start of the season in La Liga.
Even though many thought that Barcelona would lose this match, it turned out that they were still able to take advantage of scoring opportunities to win a narrow victory over Villarreal.
Villarreal is indeed a strong team, but they are no better than Barcelona, in this match I did not see that Villarreal played well, but it was Barcelona who played badly so they could concede 3 goals even when Barcelona was 2-0 up. Villarreal was able to turn things around, until finally Barcelona's players came back to make the game 4--3 but it will be another evaluation for Xavi to continue to improve this team before facing more difficult opponents.
And what is of great concern is Barcelona's bottom line this season, look at how bad Barcelona's defense is, this is a pretty serious issue if Barcelona faces a tougher team, maybe to compete in La Liga Barcelona is still quite calculated but I really don't sure they will be able to compete tightly in the UCL stage.