Cancun:Clemente Ovalle scored with five minutes left on Sunday to give Atlante a 2-1 victory over UNAM Pumas and the Mexican Apertura league title.
Ovalle's blast from 20 meters in gave the Cancun-based club its third championship and first in 14 years.
Venezuelan Giancarlo Maldonao gave Atlante the lead in the 59th minute, while Ismael Iniguez equalized for Pumas 10 minutes later.
"Thanks to God, thanks to the work that has been and one also has to recognize Pumas, who were a rival who deserved better, but only one team can be the champion," Atlante manager Jose Guadalupe Cruz said.
Cruz was a defender for the Atlante club when it won its last title in 1993. Before that, Atlante had not won the crown since 1947.
Los Potros abandoned Mexico City this season to play in Cancun due to poor attendance at Azteca Stadium.
With a small budget, they signed castoffs from other teams and opened the season with an 11-game unbeten streak. It won only two of its last six games in the regular season, but easily dismissed Cruz Azul in the playoff quarterfinals, and after a 1-1 aggregate draw with Guadalajara, advanced past Chivas in the semifinals with a better overall record.
A 0-0 draw in Thursday's first leg set up Sunday for the dramatic finale.
"This is for all of the fans that have not been able to celebrate anything. Maybe we were not brilliant, but we were consistent," Cruz said. "We faced many adversities, but we overcame them and now we have the crown."
Pumas had the better scoring chances, but Atlante goalkeeper Federico Vilar was equal to the effort.