Diego Reyes went the distance again at defensive midfielder, while Carlos Vela notched his fourth assist in three games following another good performance on both flanks.
In the 17th minute, a precise delivery from Carlos Vela on the left was dutifully gathered by Jonathas, who fired above Gorka Iraizoz to score the only goal of the match.
The result was La Real's fourth straight league victory and their eighth without a defeat against their rivals Athletic Bilbao.
The win also moves Eusebio's men to ninth in the table and three points from a Europa League spot.
You can watch Vela's assist below: