Mexico's all-time leading scorer was well marshalled by South Korea's defense for much of Saturday's clash in Rostov-on-Don, but took his chance when it came in the 66th minute, slotting home in composed fashion at the culmination of a wonderful counterattack.
Expectedly, Tottenham star Son Heung-min was their most unsafe outlet and threatened the Mexico goal a couple of times in the opening exchanges.
With a 2-0 lead in the second half, El Tri faithful took to chanting "Profe Osorio" in support of the team's Colombian coach Juan Carlos Osorio, who before the tournament had been heavily criticized by pundits and a football-loving public for his tactics and management of the national team.
Hernandez added the second in the 66th, scoring his 50th goal for Mexico.
Mexico is now 2-0 in the tournament and in strong position to advance to the elimination round, while South Korea is 0-2 and has nearly no chance of advancing.
Mexico showed their quality on the break again when Miguel Layun fired in a cross that Lozano very almost got on the end of, but they did not have to wait much longer to take the lead.
But, six minutes before the half-hour mark, El Tricolor were handed the ideal opportunity to open the scoring when opposition defender Jang Hyun-soo needlessly went to the ground in an attempt to block an Andres Guardado cross - only to handle the ball inside the area.
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Carlos Vela got the Mexicans on their way at the Rostov Arena with a 26th-minute penalty, before Javier Hernandez wrapped up the three points with a second six minutes after the hour mark.
South Korea next face defending champions Germany with very little hope of qualifying for the knockout phase, which they last reached in 2010.
Hernandez would not be denied again, though, the West Ham striker making no mistake in drilling in his landmark goal to send the raucous Mexican crowd into raptures. Heung-Min Son scored in the stoppage time to half the deficit but in the end it was no more than a consolation.
- South Korea has lost its last four World Cup matches, tied for its worst losing run at the World Cup (it also lost four straight between 1986 and 1990).
Conditioned by the dry heat that has been a feature of every game at the Rostov Arena, Mexico did not quite have the same thrust and energy as against Germany although they still controlled most of the play and looked far more risky. But history was not on Mexico's side because it had not won back-to-back matches at a World Cup since 2002.
Oddsmakers favor Mexico, most likely due to its stirring performance last Sunday in its upset win over Germany and overall World Cup pedigree - nine wins, seven draws and just two losses in its last 18 World Cup group-stage games.