The Asian giants were denied two points by Aleksandr Kerzhakov's equaliser for Russia while the north Africans fell victim to a late Belgium comeback in Belo Horizonte
South Korea and Algeria still have everything to play for when they face each other at Estadio Beira-Rio for their second Group H fixture.
Both teams lost points from winning positions in their first matches. Algeria were undone by two second-half Belgian goals after a 25th-minute penalty from Sofiane Feghouli had given them a shock lead over the group favourites, while Aleksandr Kerzhakov rescued a point for Russia against South Korea.
Algeria's defensive approach invited Belgium to complete their comeback in the last 20 minutes at Mineirao, something coach Vahid Halilhodzic knows his team cannot afford to replicate in Porto Alegre if they want to make a serious qualification push.
"I feel very disappointed. We missed it. We could have won. My players allowed Belgium to hold and use the ball for too long without chasing and breaking," he said after the match.
Now they are expected to show some of the attacking prowess they exhibited in the CAF Qualifiers, with goalscorer Islam Slimani an option in attack, although El Harbi Soudani should retain his spot. Whichever man Halihodzic goes with, they will be expected to benefit from Sofiane Feghouli's skill and creativity in midfield.
The South Korean side, for their part, will also be determined to get a better result on Sunday, with coach and former World Cup veteran Hong Myung-bo praising the Warriors' performance against Russia last time around, despite suffering a late equaliser in a fairly even match.
"I want to thank to my players, who did their best until the last minute", the coach said. "I think it worked well. The condition of the players and the organisation of the team was good."
No big changes should be made from the 4-4-2 that almost secured victory over the Russians a few days ago, with attacking starters Heung-Min Son and Chu-Young Park expected to do better in southern Brazil.