South Korea booked a knockout spot at the FIFA U-17 World Cup in Chile on Tuesday.

South Korea defeated Guinea 1-0 for their second straight victory in Group B at Estadio La Portada in La Serena, as Oh Se-hun scored the dramatic winner in the dying moments.

South Korea have secured a spot in the round of 16, regardless of their result against England in their final group match Friday.

This will be South Korea's first appearance in the round of 16 at the youth event since making the quarters in 2009. The country didn't qualify for the 2011 and 2013 events.

South Korea earlier defeated Brazil 1-0. It marks the first time South Korea have won the first two matches of the group stage at any FIFA men's tournament.

Guinea looked to be in control early, before dynamic attacker Lee Seung-woo took over the match, making sharp passes deep in the Guinea zone and firing at the net with abandon.

Guinea fought back late in the first half, with Naby Bangoura and Yamodoue Toure pushing the defense.

South Korea nearly broke the deadlock in the 73rd. Lee Seung-woo launched a free kick that was kept out by goalkeeper Moussa Camara, and the rebound went right back to the charging Park Myeong-su.

The Guinean goalkeeper stood his ground and denied Park on the close-range shot.

Oh Se-hun entered the game in the first minute of injury time and netted the winner in the very next minute, converting a feed by You Ju-an.

South Korea head coach Choi Jin-cheul said his players still have a lot more to show on the pitch.

"So far, we've played strong defense and mounted effective counterattacks," he said. "But I think we could become a bit more aggressive. We have players who are capable of doing just that.

Guinea were a difficult opponent, but we were able to take advantage as their defense grew weaker in the second half."

Oh, the goal scorer, said the big moment still hadn't hit him after the match.

"I don't even remember what happened; it was so incredible," he said. "I just wanted to do what the coach asked me to do and help the team win as much as I could."

There are 24 nations paired into six groups of four. The top two teams from each group, plus the four best runners-up, will make up the round of 16.

Should South Korea win Group B, they will face one of the third-place seeds. If South Korea end in second in Group B, they will meet the runner-up from Group F.

South Korea can take Group B with a draw against England. (Yonhap)