Daniel Luduena's goal in the 73rd 1 win over Jaguares in the second leg of their quarterfinal 3 aggregate win.
The two sides played to a 2-2 draw in the opening leg before Carlos Quintero's first-half goal put Santos in front.
Jackson Martinez equalized for Jaguares in the 66th minute, but Luduena provided the winner 17 minutes from time, allowing his team to advance to the next round, where they will face Morelia.
First-half goals from Miguel Sabah and Edgar Lugo helped Morelia to a 2-1 win over Cruz Azul in the second leg of their quarterfinal contest, giving Morelia a 4-2 aggregate win, while Guadalajara and Queretaro finished in a 0-0 draw in Saturday's other match, helping Queretaro reach the semifinals on aggregate, 2-1.
Queretaro's opponents in the next round will be Tigres, which coasted to a 4-0 aggregate win against Pachuca after a 3-0 triumph in the second leg on Sunday.
Tigres scored three times in the first 35 minutes of the game before Pachuca was reduced to 10 men in the second half as Hector Herrera was sent off.