Andreas Granqvist emerged as the hero for the Swedes as he kept his cool to convert a 65th-minute penalty, which ultimately proved enough to decide the contest.
Referee Joel Aguilar used the replay technology to decide whether South Korea substitute Kim Min-woo had fouled Viktor Claesson in the area after initially waving play on. Sweden had not won an opening game at any World Cup since 1958, when they were runners-up in their best performance to date.
Before Granqvist's penalty, Sweden showed most of the attacking intent at Nizhny Novgorod Stadium.
South Korea: Cho Hyun-Woo 8, Lee Yong 6, Kim Young-Gwon 8, Jang Hyun-Soo 6, Park Joo-Ho 6, Lee Seung-Woo 6, Koo Ja-Cheol 6, Ki Sung-yueng 6, Lee Jae-Sung 6, Hwang Hee-Chan 6, Son Heung-Min 6.
The proverb may have been disproven Monday as Sweden fought to a 1-0 victory against South Korea after a Swedish assistant admitted he spied on the opponents' training sessions from a rented house.
Sweden hadn't scored a goal in over 400 minutes and there was cause for concern when Janne Anderson's side had failed to find the breakthrough after an hour of play, despite creating numerous opportunities.
It had been 402 minutes since Ola Toivonen scored Sweden's last worldwide goal against Chile back in March.
Centre-half Granqvist stepped up to coolly slot home the penalty to claim all three points and send Sweden top of the group, level with Mexico on three points.
Andreas Granqvist (left) celebrates with teammate Albin Ekdal after scoring from the penalty spot against South Korea.
"This is something small that has been turned into something much bigger because usually our information about our opponents comes from us watching them play matches".
Both teams' star players provided their creative drive, Son Heung-min trying to drive Korea forward from the left flank but again failing to have the same impact on the global stage as he does in the Premier League. "The pressure is on them", said the ebullient Granqvist. Meanwhile, goalkeeper Robin Olsen was named in the line-up after recovering from a shoulder injury that had threatened his World Cup participation.
He also made a couple of crucial interventions at the other end of the pitch to cap an excellent captain's display as Sweden got their campaign off to a winning start.