Puebla came from two goals down to draw 2-2 against Toluca on Thursday in the Liga MX Apertura 2015 quarterfinal first leg.
Second-half goals from Luis Gabriel Rey and Roberto Herrera salvaged a draw for Puebla, after Omar Arellano and Fernando Uribe had put Toluca 2-0 up in the first 45 minutes.
The teams will go into Sunday's second leg, but the away-goal rule is in place and makes Toluca the favorite to advance.
Arellano scrambled in the opener after quarter of an hour, after Puebla keeper Cristian Campestrini parried an Enrique Triverio shot into his path.
Toluca's second came from a simple Uribe header, following a cross by Carlos Esquivel. The goal silenced the close to 50,000 fans in Puebla's recently redeveloped Estadio Cuauhtemoc.
Puebla came out for the second half with much more attacking intent and the game flowed from end to end, with both goalkeepers forced into regular action.
Rey pulled the first back for Puebla when he headed in six minutes into the second half, with defender Herrera mishitting the equalizer into the roof of the net from close range in the 87th minute to send the crowd wild.
In-between Puebla's goals, Toluca's Esquivel hit the crossbar in the 57th minute with a shot from long range.
Toluca finished the regular season in second place, with Puebla in sixth, qualifying for its first playoff series in six years.
In Thursday's other match, eighth-seed Veracruz defeated regular-season leader Pumas 1-0.
Argentine Daniel Villalva netted the only goal in the 7th minute, with the forward finding himself free from a right-wing cross to head in at the far post.
The result in Estadio Luis "Pirata" Fuente hands Veracruz a significant advantage ahead of Sunday's second decisive leg inside Estadio Olimpico Universitario, with the away-goal rule counting.
The result could've been worse for Pumas. Veracruz came storming out at the start of the match and had enough chances in the first half to win by more than one goal.
Pumas goalkeeper Alejandro "Pikolin" Palacios was the player of the match and produced a flying save from Fernando Meneses in the 5th minute.
Veracruz also had two goals disallowed in the first 45 minutes, as Pumas hung on and struggled to take any control of the match.
Pumas, one of the favorites to win the Apertura title, did improve after the break, although Palacios was once again forced into a decent save from Juan Albin just after the hour mark.
There was also controversy in second-half injury time when Luis Fuentes brought down Villalva, with the referee giving a free-kick on the edge of the area, when TV replays suggested the foul occurred inside the box.
In Wednesday's other quarterfinal first legs, America defeated Leon 4-1 and Tigres won 2-1 against Chiapas.