Both sides have just grabbed a win in Copa del Rey respectively after beating Real Madrid and Barcelona who are now top 2 teams in La Liga. Now they are both in high morale.
The AH line is -0.25 for the hosts, so Real Sociedad fail to earn enough support from the bookies. Besides, Athletic Bilbao have a high unbeaten rate on away field.
So Athletic Bilbao are expected to remain unbeaten in this away match.