Rogelio Chavez scored the only goal of the game from the spot eight minutes into the second half, but the hosts - beaten finalists in last season's Clausura - were forced to dig in late on after Gerardo Torrado saw red in the 84th minute.
Angel Reyna scored a 90th-minute equaliser as top-flight newcomers Veracruz twice came from behind to claim a 2-2 draw against Jaguares.
Aviles Hurtado twice put the visitors ahead, in the 22nd minute and then with an 84th-minute penalty, but Veracruz levelled first thanks to Luis Tejada's spot-kick in the 53rd minute, then through Reyna's last-gasp effort.
Mauricio Castaneda scored nine minutes from time as Leon left it late to beat 10-man Atlante 1-0.
The visitors played most of the game a man down after Jose Fonseca (11) was sent off.