I don't think Barcelona is lucky to start this season with a nucleus team like Mallorca because Barcelona is so strong that they can defeat any team in the LaLiga this season. I think Mallorca is the unlucky team here because they will be starting this season with a defeat, yes obviously Mallorca is a nucleus team that is weaker to go against a strong team like Barcelona. Offcourse they are definitely going to be trash by Barcelona with a large margin. I don't think Barcelona will be joking around with the mindset of underestimating Mallorca in today game especially when they now have a strong Rival like Real Madrid.
I don't think you should underestimate any team right now football is never and will never be easily predictable, football is so surprising it might shock us that Mallorca can hold Fc Barcelona to a draw, and also they are going to play the match in Mallorca stadium (Campo de fútbol de Son Moix), and you fully known that every team will always want to play more effective in their home, not that am trying to place Mallorca as the favorite but i think the game won't be as easy as you are thinking, yet like i predicted earlier Barcelona can make first three point from today's game. This game will really have a good and high odds to bet on.
Having Real Madrid as a rival to any club is really tough to handle from Barcelona team because this season Real Madrid won't want to go trophy less again just like last season.