The victory moved Javier ​Aguirre’s side onto six points from two matches and ensured their first knockout game would be played in Mexico City ‌on June 30.

They are the first team to qualify for the knockout stage.

Romo broke the deadlock three minutes after the restart, capitalising on a costly mistake by goalkeeper Kim Seung-Gyu.

The South Korea keeper spilt a cross after colliding with a teammate, allowing the Mexico midfielder a simple finish into an unguarded net from ​the centre of the box.

“It was a very close game; we didn’t give up a single centimetre and fought for every ​ball as if it were our last,” Aguirre told Mexican broadcaster TV Azteca.

“It was a game where whoever ⁠made a mistake would lose, and it was them… It was a game to forget, but the result is one to remember.”

The goal ​transformed the mood inside Guadalajara Stadium after an uninspiring first half that ended with sections of the home crowd booing the hosts off the ​pitch.

Mexico had started brightly but struggled to turn early possession into clear chances, with South Korea growing into the game.

Captain Edson Alvarez, deployed in central defence after Cesar Montes’ suspension, produced a spectacular overhead clearance off the goal line to deny Son Heung-min, although the South Korea captain was later flagged offside.

The Asian side finished ​the half stronger, controlling possession and unsettling a Mexico side that looked increasingly frustrated as the interval approached.

HOSTS WEATHER LATE STORM

Romo’s goal moments ​after the restart lifted both Mexico and the crowd, with supporters breaking into renditions of Mexican folk song “Cielito Lindo” (“Lovely Sweetheart”) as Aguirre’s side seized control of a ‌match ⁠that had threatened to drift away from them.

Mexico nearly doubled their advantage midway through the second half when Raul Jimenez controlled a pass from Julian Quinones before firing a half-volley from close range, only for Kim to produce an outstanding save.

The South Korea goalkeeper made another excellent stop to deny substitute Obed Vargas, diving low to push away a powerful long-range effort.

South Korea threw numbers forward in search of an equaliser and ​came agonisingly close in the closing ​stages, but goalkeeper Raul Rangel preserved ⁠Mexico’s lead with a remarkable double save from point-blank range.

Rangel first blocked a close-range effort with his foot before scrambling across his line to keep out the rebound.

Mexico withstood wave after wave of South Korean ​pressure in a tense finish to secure their second straight win and become the first team to ​qualify for the knockout ⁠stage, where they will face a third-placed team.

The result also gave Mexico their first World Cup group-stage victory on home soil outside Mexico City and secured their first top-place finish in a World Cup group since 2002, when Aguirre was also in charge.

Aguirre’s side will close out the group phase ⁠against Czech ​Republic, while South Korea can still secure progression when they face South Africa on ​Wednesday.

“We were patient, not passive. It’s not easy, we’re seeing some very close matches,” Aguirre added.

“We’ll see how the last match plays out and wait for our opponent. I’m leaving ​happy because it means we’re not leaving home, our beloved Mexico.”