Michaell Chirinos scored in the second half as Lobos BUAP beat Chivas Guadalajara 1-0 at the Estadio Akron to add further misery to the Rojiblancos.
The defeat means Chivas are five points away from eighth place Puebla with only four games left to play in the regular season.
Chivas, who arrived to this match on the back of two straight Liga MX defeats, started on the front foot. Alexis Vega created the first big opportunity of the game when he sent a shot just inches wide of the Puebla goal.
Vega would eventually put his name on the stat sheet but not for a good reason. Close to the end of the first half, Vega was sent off for a kick on an opposing defender.
After 59 minutes, Lobos had their first big chance of the game when Bryan Rabello nearly turned the ball in straight from a corner kick, hitting the woodwork in the process.
With the game approaching its final 10 minutes, Lobos found their winner. A deflected cross from Mauro Lainez fell into the path of Michaell Chirinos, who headed past Miguel Jimenez to give the Poblanos their third straight Liga MX win.