Two own goals from Mario Hermoso condemned Espanyol to a 2-0 defeat at Leganes and heightened the pressure on Coach Quique Sanchez Flores.
The Madrid-based side, who recently qualified for the Copa del Rey semi-finals for the first time in their history, took the lead in the 11th minute, when the defender put through his own net.
Marc Navarro fired the visitors level just after the break, but Miguel Angel Guerrero headed Leganes back in front 20 minutes from time.
The unfortunate Hermoso then inadvertently deflected Nordin Amrabat’s cross into his own net, before he netted a late consolation from goalkeeper Ivan Cuellar’s header.
Leganes rise to 11th in the standings, while Espanyol remain down in 14th.