After the teams ended 120 minutes of regulation and extra time knotted at 3-3, South Korea prevailed 3-2 in the penalty shootout in the quarterfinals at Bielsko-Biala Stadium in Bielsko-Biala, Poland.
The first two South Korean kickers missed before the fifth taker, Oh Se-hun, converted the decisive chance. Cavin Diagne, Senegal's last kicker, missed the target high, as South Korea reached the semifinals of the top youth tournament for the first time in 36 years.
South Korea will have a chance to advance to the final for the first time when they take on Ecuador in Tuesday's semifinals. South Korea defeated Ecuador 1-0 in a tuneup match on May 17.
Since dropping the first group match against Portugal in Bielsko-Biala on May 25, South Korea have reeled off four consecutive victories.
The roller coaster of a match featured two penalties in regulation and two last-gasp equalizers by both sides, along with a series of momentum-swinging video reviews.
South Korea were on the brink of elimination, before defender Lee Ji-sol came to the rescue with a stoppage-time header to level the score at 2-2.
Forward Cho Young-wook netted the go-ahead goal six minutes into extra time. South Korea were closing in on a dramatic victory after surviving some nervy moments, but Amadou Ciss scored the equalizer merely seconds before the final whistle to set up the penalty shootout.
With South Korea shooting first, Kim Jung-min hit the low part of the left post as the team's first kicker. Mamadou Danfa put Senegal on the board as their first taker.
Goalkeeper Dialy N'Diaye denied Cho on South Korea's second shot, but Mamadou Mbow missed the net high to give South Korea an opening.
Um Won-sang for South Korea and Ciss for Senegal each converted their chance, with Senegal still up 2-1.
Choi Jun's successful kick made it 2-2 for South Korea, and goalkeeper Lee Gwang-yeon denied Dia N'Diaye with a diving save to his right.
Oh was denied by Dialy N'Diaye on the initial shot, but the Senegalese keeper was booked for taking both of his feet off the goal line before a shot was taken -- a violation under the new rules.
Given a new chance, Oh beat N'Diaye clean this time to put South Korea up 3-2. Diagne, who'd opened the scoring for Senegal in the 37th minute, airmailed his shot above the net, as South Korea celebrated a storybook victory.
After an evenly matched opening stretch, Senegal began to assume control of the match midway through the first half. Senegal ratcheted up the pressure and earned three straight corner kicks in a two-minute span. The third one resulted in the opening goal, as Cavin Diagne took advantage of a botched clearing attempt and beat Lee with a volley to the top left-hand corner.
South Korea turned their offensive intensity up a notch in the second half. Then at the hour mark, South Korea were belatedly awarded a penalty following a video review, after Lee Ji-sol was shoved from behind by an opposing player inside the area.
Lee Kang-in stepped up and beat Dialy N'Diaye to the bottom left corner to level the score at 1-1 in the 62nd minute, but Senegal went ahead 14 minutes later, with the video replay at the center of it all again.
Lee Jae-ik was called for a handball violation in the box upon video review. Ibrahima Niane took the spot kick, and Lee Gwang-yeon made a stop diving to his left, but the South Korean goalkeeper was booked for leaving the goal line before the shot.
Niane beat Lee to the right side on his second opportunity for a 2-1 lead for Senegal.
South Korea caught a couple of late breaks. An 86th-minute Senegal goal was wiped out due to a handball violation by an offensive player. Senegal put another one past Lee Gwang-yeon in the 89th minute, but it was called back on an offside ruling.
And South Korea took advantage of that opening. With the clock ticking down, Lee Ji-sol snuck in from behind and headed home a Lee Kang-in corner kick to send the match into extra time.
With the momentum on their side, South Korea took the lead on an early counterattack opportunity in extra time.
Oh Se-hun stole the ball in midfield and flicked it over to Lee Kang-in, who then threaded a perfect pass through multiple defenders for Cho. The super sub then fired it to the top shelf, well out of N'Diaye's reach.
South Korea came within seconds of sealing the victory in extra time, but Ciss scored the equalizer from Danfa's pass to set up the shootout.
Things looked bleak for South Korea after their first two kickers failed to convert, but Senegal also went on to miss twice, and Lee Gwang-yeon rose to the occasion with a stop. (Yonhap)