Brazilian striker Jonathas fired his fourth goal in three matches to clinch Real Sociedad a 1-0 Primera Division win at Basque derby rivals Athletic Bilbao.
Jonathas struck the game's only goal in the first half with a thumping finish as Sociedad maintained their climb up the table with a fourth consecutive league win.
The two sides produced a goalless stalemate in their previous meeting at the Anoeta in September, but both carved out a series of chances on Sunday before the hosts ran out of steam in the closing stages.
Victory lifted Sociedad up to ninth place and within two points of Athletic, whose third home league defeat of the season denied them a place in the top six.
Sociedad defender Diego Reyes fired an early effort from outside the penalty area just over the crossbar, while Athletic went close in the 14th minute when midfielder Benat's shot was saved by the legs of visiting goalkeeper Geronimo Rulli.
Jonathas served warning for the home team with a low shot that was superbly saved by Gorka Iraizoz, but the Athletic goalkeeper was emphatically beaten by the Sociedad striker soon after.
Mexico international Carlos Vela slipped the ball down the left edge of the area and Jonathas crashed home a rising shot to give Sociedad a 17th-minute lead.
Athletic, who appeared sluggish from their efforts in the Europa League on Thursday when they won 1-0 in Marseille, stirred themselves and Markel Susaeta, Iker Muniain and Mikel San Jose all had shots blocked as they chased an equaliser.
But Jonathas went close to doubling Sociedad's lead in the 31st minute when his low shot was saved by Iraizoz at full stretch in the corner.
Athletic striker Inaki Williams was forced off through injury in the 37th minute and replaced by Raul Garcia.
Iraizoz kept Sociedad at bay again in first-half stoppage time with a fine save to deny Vela.
The hosts were first to threaten in the second half as Raul Garcia's header from Susaeta's cross flew inches over Rulli's top-left corner and Benat pulled his shot wide before Aymeric Laporte's brilliant effort from an acute angle was saved by the visitors' goalkeeper.
Aritz Aduriz was next to threaten as Athletic continued to chase the game, but he pulled his 67th-minute shot wide following a corner and team-mate Muniain blazed over when well placed five minutes later.
Sociedad countered immediately after and Ruben Pardo lashed an effort from the edge of the box inches over the crossbar having been teed up by Jonathas.
Athletic, clearly feeling the affects of their European exploits, failed to create any further goalscoring chances in the closing stages, while Sociedad midfielder Xabi Prieto blasted off target when well placed in the 89th minute.