South Korea fought back from a goal down to claim a deserved 2-1 win over Group A rivals Czech Republic in the second game of the World Cup at Estadio Guadalajara.
Myung-Bo Hong's side were the better team throughout but fell behind after several misses from Heung-Min Son when Ladislav Krejci headed home Vladimir Coufal's second-half long throw.
Czech Republic's lead only lasted eight minutes, however, with In-Beom Hwang drawing South Korea level when he cut inside from Kang-In Lee's pass and clipped a deft finish inside the post.
Tomas Soucek thought he had put the Czechs back in front when he headed in from another set-piece, but the West Ham midfielder was flagged for offside before South Korea substitute Hyeon-Gyu Oh tucked home In-Beom Hwang's low cross for the winner.
The victory puts South Korea level on points with Mexico, 2-0 winners over South Africa in the opening game, in Group A and rewards an impressive team performance in which they demonstrated a high level of technical quality.
On the evidence of their performance in Guadalajara, South Korea should not be underestimated at this tournament. They were deserving winners in a game defined by a clash of styles.
Czech Republic's inclination to go direct was evident from the early stages of the game. It was fitting that their goal came from a long throw. They struggled to create openings in open play.
South Korea, though, played with verve and imagination, taking a 62 per cent share of possession and completing nearly twice as many passes as their opponents with 464 to Czech Republic's 242.
Son is of course the face of the team. The former Spurs forward featured prominently in the game but lacked the cutting edge of old as he sent all but one of his six shots off target.
It speaks to their depth of quality, though, that South Korea could score the goals they needed anyway. Both of them were superbly-worked, featuring starring contributions from In-Beom Hwang and Kang-In Lee, the game's two outstanding performers.
South Korea now look set to battle with co-hosts Mexico for top spot in Group A. They have the look of potential dark horses after this impressive opening display.
Hyeon-Gyu Oh, the scorer of South Korea's winning goal, revealed he almost missed the game entirely having felt unwell in the build-up.
"I cannot explain my emotions in words," he said. "My body temperature today had gone up to 38 degrees because I wasn't feeling well.
"I wondered if I could even play. It was possible thanks to our staff, and medical team. Playing at the World Cup itself is something that I should be grateful and thankful for. As a striker I am relieved and thankful."
Head coach Myung-Bo Hong, meanwhile, praised his side's mentality.
"It was our first game and a very difficult one. The win itself makes me happy, but what's even more positive is that our boys won by not giving up.
"I knew that we were more than capable of winning, so at 1-1, I told the boys to keep playing the way we've been playing."
Czech Republic coach Miroslav Koubek rued "some mistakes" but admitted "the better team probably won".
"We played very well, it could have been a draw and we could have won as well," said Koubek, whose side face South Africa in their second group match on Thursday.
