Tomas Boy looked to be coaching for his job in this weekend's Clasico Nacional, but Chivas decided to act sooner, dismissing the manager ahead of Saturday's rivalry match and announcing Luis Fernando Tena will be the new manager.
Chivas currently sit in 15th place with 10 points in the Apertura, putting the Guadalajara team four points away from the eighth and final playoff spot with eight rounds of matches still to be played.
Boy, who took over in April, earned just 14 out of 45 possible points, leaving the club with a 4-9-2 record including Tuesday's 4-2 loss at home to Pachuca.
He reportedly met with the directors of the club, which signs only Mexican players, Wednesday and was set to press on pending the result of Saturday's match against rival America, but now has been given his marching orders.
"Club Deportivo Guadalajara announces that Luis Fernando Tena will be, from today, the new manager of the first team. 'El Flaco', who during his time as a player wore the shirt of the most Mexican team for three years and is a winning tactician on the international level," a club statement read.
"Club Deportivo Guadalajara is confident that the experience, temperament and knowledge 'El Flaco' has in the direction of national players will be a key push from now on to get the Rebano Sagrado back into the historic position that its tradition and fans demand," it continued.
Tena most recently coached in Liga MX with Queretaro, but perhaps his greatest achievement came in 2012 when he guided Mexico's U-23 team to Olympic gold in London.
He also coached Cruz Azul to its last league title in 1997 and led Morelia to its only league title in 2000. He also helped Cruz Azul to a Concacaf Champions League crown in 2014.
The 61-year-old developed at now-defunct Atletico Espanol and moved to also defunct Oaxtepec before playing for Chivas and later closing out his career with Atlante.
He got into coaching in 1994 with Cruz Azul and led La Maquina during four separate stints. Chivas will be the 10th Liga MX team he has managed.
Tena becomes the 24th manager of Chivas since Jorge Vergara purchased the historic club in 2002