Malaga have been beaten at home for the first time in 13 games by Rayo Vallecano.
With the first real chance of the game after 11 minutes, Piti put Vallecano in front after being set up by Leo Carrilho.
Malaga pushed for the equaliser and went close through Jesus Gamez, but his shot missed the target.
Joaquin Sanchez tested Cobeno in the away goal just after the half-hour, but the goalkeeper kept out the shot well.
Eliseu rose well for the hosts just before the break but he missed the target with a header.
Just four minutes into the second half Malaga were level when Martin Demichelis headed in a Sanchez cross.
Vallecano regrouped well and were in front again on 61 minutes through the same combination as their opener.
Malaga huffed and puffed but were unable to create any real chances as Vallecano held on for a huge win.