Atlas missed the chance to go two points clear at the top of the Clausura table with one game to play as they were held to a 1-1 draw at Puebla on Sunday.
Atlas appeared to be heading for victory when Vicente Vuoso put them ahead 10 minutes from the end, but the lead lasted just four minutes before Jonathan Lacerda levelled.
The draw left Atlas level on points with leaders Club America and second-placed Tigres Monterrey, but third on goal difference.
The point for Puebla also relegated Queretaro, who nevertheless went on to claim a 2-1 win at Guadalajara despite playing over an hour with 10 men.
Gonzalo Pineda was dismissed after 28 minutes but a Sergio Perez own goal put the visitors ahead after 37 minutes and Wilberto Cosme extended the advantage seven minutes into the second half.
Abraham Coronado pulled one back for Guadalajara, but it was not enough to prevent Queretaro, who will be relegated by results over the last three seasons, taking what were three consolation points.
In the day's other game, Javier Cortes scored twice and Robin Ramirez also netted as Unam Pumas sealed their place in the Liguilla with a 3-0 win over Jaguares.