Two goals from second-half substitute Giovani dos Santos secured the three points; the first a breakaway goal created by fine work from Oribe Peralta and clinically dispatched by the Tottenham outcast, before he converted an injury-time penalty.
Mexico coach Luis Fernando Tena named an unchanged line-up, meaning Dos Santos started on the bench once more. Gabon’s Claude Mbourounot made one change with Axel Meye coming in for Allen Nono.
El Tricolor had two glorious chances to take the lead inside six minutes; first Marco Fabian’s shot from the edge of the area was palmed away by Gabon’s Didier Ovondo before Miguel Ponce headed wide from close range moments later.
Tena's men looked a far better side in the opening stages than they did at any point against South Korea in their opening game, however Gabon continued to carry a threat in attack, particularly through Pierre Aubameyang.
The West African’s also looked dangerous on the left flank through Jerry Obiang Obiang, who found himself in good positions on a number of occasions but a couple of poor first touches and a tame effort on goal kept the scores level at the break.
Tena brought on Dos Santos for the start of the second half in place of Ponce as Mexico stepped up their push for a goal.
That breakthrough almost came just seven minutes later Peralta struck a goal-bound curling shot, but Gabon keeper Ovono somehow managed to get his fingertips to the ball to tip it around the post.
The deadlock was eventually broken after an hour and it was the substitute who made the difference. Following some fine hold up play from Peralta, Dos Santos arrived in the nick of time and slotted a side-footed finish past Ovono to score Mexico’s first goal of the tournament.
Mexico’s goal sparked some life into the Gabon team who surged forward looking for an instant reply, only to leave themselves vulnerable at the back with Peralta and Dos Santos a constant threat on the break.
Aubemayang squandered two fine changes for Gabon as looked for a way back into the game, first opting to cross when he had a chance to shoot and then failing to beat Corona at his near post when he found himself clear through on goal.
Late substitute Samson Mbingui almost nodded in the equaliser with his first touch but the Mexican defence managed to block his effort and scramble the ball away to safety.
It then went from bad to worse for the African's as Henri Ndong hauled down Peralta to award Mexico a penalty and earn himself a second yellow card in the process. Dos Santos stepped up and dispatched the spot-kick with ease to cap a fine second-half cameo.