Chicharito bagged his 50th goal in worldwide play on a counter-attack led by breakout star Hirving Lozano - but Mexico was only able to score because referee Milorad Mazic allowed play to continue after Hector Herrera fouled Ki Sung-yueng to gain possession.
Mexico will not be over-confident when they play South Korea in their Group F game at the World Cup on Saturday, aware that their opponents may adopt any of a number of formations to outsmart the team that beat holders Germany in their opener. And all of them should be afraid of Mexico.
However, Jang Hyun-soo's handball gave referee Milorad Mazic little choice but to point to the spot - the number of penalties awarded in Russian Federation consequently surpassing the 13 across the entirety of the previous World Cup - and Vela, who announced the death of his grandfather following the win over Germany, converted.
All-time top scorer Javier Hernandez sealed victory in the second half, finishing off an unstoppable move from breakout player Hirving Lozano. The 57th-ranked South Korea lost to Sweden 1-0 in their first group match on Monday, a dispiriting performance in which they didn't record a shot on target.
After losing their opening game against Sweden, a win was key for South Korea's hopes of making it out of the group.
Mexico's second goal could have knocked the stuffing out of South Korea as Hernandez cut inside his marker and scuffed a finish past a helpless Cho, but still the 2002 semi finalists continued to fight and attempt to mount a comeback. Carlos Vela converted the penalty with a wonderful strike sending the keeper the wrong way to give his side a 1-0 advantage.
Vela coolly hands Mexico the lead from the spot.
It was Lozano returning the favor to his teammate after Hernandez assisted on Lozano's goal against Germany in a similar play.
With six chances created across his two games, only four players at the World Cup have been more creative than Vela so far: Kevin De Bruyne (nine) and Neymar, Philippe Coutinho and Joshua Kimmich (seven).
And his appearances have not just been as a tribute, as you see towards the end of club seasons, with the 39-year-old still putting himself about shutting down games.
So, two teams with two very different mindsets heading into this one. The shutout was Mexico's sixth in its past eight games.
The criticism of Mexico's national team heading into the World Cup was loud and scathing.
Mexico were quick out of the traps in the opening half, pressing forward and passing well around the Korean team. Only Russia's Roman Zobnin (eight) has more.
Mexico started aggressively, pressuring their rivals all over the field, while South Korea was happy to sit back and wait for some chances through counter-attacks, but it was clear that Mexico is a better side than the Taegeuk Warriors.
But Mexico proved themselves to be a big threat against South Korea with the only way the Asian nation could stop them being illegally.
"We have to keep playing as well as we did against Germany and we have to have the same mindset", Guardado said.