FC Barcelona
They are the third in the table of the League. It is unlikely for them to win the title for the reason that there are eight points separating them from the first, Atletico Madrid. But over-scheduled matches in these days drives them fatigued.
Alaves
They get 1W-1D in recent games. The most important thing for them at present is to avoid relegation as they are the sixteenth in the table of the League. They do not play well as traveller, getting 20% winning percentage in away games this season.
Verdict:
FC Barcelona are certainly better than Alaves. However, FC Barcelona have to prepare for UEFA Champions League next week. It seems that they will not try their best in the upcoming game. Perhaps it is a good chance for Alaves to take points from FC Barcelona.
FC Barcelona VS Alaves
Prediction: draw