An early penalty from Carlos Vela put Mexico ahead, and Javier Hernandez's second-half goal secured the Central Americans' second straight victory after stunning reigning champions Germany in their opening game, despite a late consolation from Son Heung-min.
Although there were periods of the game where Mexico struggled to create much, you always sensed that they were not far off from a moment where they could create a chance.
Los Angeles FC forward Carlos Vela scored a penalty to open the scoring in front of a vibrant crowd in Rostov-on-Don, with West Ham's Javier Hernandez adding the killer second after half-time.
If South Korea go behind, too, they are not as likely to score as Germany were.
ESPN's Tom Marshall discusses why Mexico must refocus after their Germany win to beat South Korea.
Although Mexico performed very well against South Korea, they were found to be leaky in defence, at times conceding chances which on this occasion were not taken. "We just want to forget the criticism and the dark comments". Six of the penalties were awarded after video reviews.
After failing to generate any offense in a 4-3-3 setting against Sweden, South Korea head coach Shin Tae-yong reverted to a more familiar 4-4-2, with two players, midfielders Moon Seon-min and Ju Se-jong, making their World Cup debuts.
South Korea will be eliminated if Sweden wins or draws.
South Korean forward Son Heung-min scored a scintillating consolation goal in injury time but it was too little too late for the East Asian nation, which now can not qualify for the first knockout stage of the tournament.
World Cup - Group F - South Korea vs Mexico - Rostov Arena, Rostov-on-Don, Russia - June 23, 2018 Mexico fans inside the stadium before the match.
Mexican fans avoided using a chant, which is considered to be homophobic by Federation Internationale de Football Association, against the opposing goalkeeper.
The Taeguk Warriors are in dire need of a win if they are to remain in contention for the last 16, having lost 1-0 to Sweden in their tournament opener in Nizhny Novgorod.
According to oddsmakers, Mexico is a -149 favorite to win on the moneyline.
Korea improved on their opening defeat by Sweden although their main tactic consisted of searching for Son with long balls behind the defensive line.
Of those duels won by Mexico, 33 have been tackles, more than any other team in the tournament, with Hector Herrera leading the way for El Tri with seven.