Eibar climbed above Celta Vigo in LaLiga with Fran Rico's early goal securing a 1-0 victory.
Celta came into the contest full of confidence after a three-game unbeaten run had taken them into the top eight.
But they ended the night with nine men as Sergio Alvarez and Hugo Mallo were both sent off in stoppage time.
Eibar's morale had taken a blow with one win in five games undoing much of their early-season promise.
But Rico's ninth-minute strike took Eibar back into the top half of the table.
Celta were punished for a slow start which saw goalkeeper Ruben Blanco tested as early as the second minute by Sergi Enrich.
Eibar continued to swarm forward and Enrich crossed for Adrian to strike the crossbar with a firm header.
But Celta did not heed the warning and seconds later Rico found space in the centre of the penalty area to sweep the ball home.
Celta did not threaten until the 20th minute when Josep Sene forced a routine save from Asier Riesgo.
Theo Bongonda also tested Riesgo on the stroke of half-time, but Eibar were well worth their interval lead.
The home side almost doubled their advantage through Adrian just after the restart and Florian Lejeune's free kick forced an excellent save from Blanco as Celta lost their discipline.