Sweden marked their first appearance in the World Cup for 12 years by beating South Korea thanks to a penalty from captain Andreas Granqvist that was awarded after a video assistant referee (VAR) review.
There was a short delay for Kim Min-woo's foul on Viktor Claesson to be analysed on video and for the referee to point to the spot but it did not affect Granqvist, who sent goalkeeper Cho Hyun-woo the wrong way.
Sweden, who join Mexico at the top of Group F on three points, created the better chances in Nizhny Novgorod.
Marcus Berg should have scored midway through the first half but his close range shot was beaten away by Cho, while South Korea did not manage a single shot on target.
In a scrappy game, Cho also saved well from Ola Toivonen's header following a free-kick.
South Korea, competing in their ninth successive World Cup, were disappointing and the closest they came to scoring was when Hwang Hee-chan headed wastefully wide in the closing moments.
The result means Mexico, 1-0 winners over world champions Germany on Sunday, and Sweden have a three-point lead after the first round of matches in Group F.
Andreas Granqvist is the first Swede to score a penalty at the World Cup since Henrik Larsson in 2002 against Nigeria
Gritty Swedes get vital win
Sweden qualified by finishing above the Netherlands in qualifying, beating France in a group game and then overcoming Italy in a play-off.
However, they arrived in Russia without a goal in their previous three matches and without Zlatan Ibrahimovic following his retirement from international football.
Indeed, Janne Andersson's team looked to be heading for a goalless draw until the second-half penalty.
There was little doubt about the spot kick as replayed showed Claesson, who plays his club football in Russia, was clearly caught.
It was however a gritty rather than spectacular performance from the Swedes, who lost Manchester United defender Victor Lindelof on the morning of the game due to illness.
His place was taken by Pontus Jansson but in truth the Leeds United player had little to do against lacklustre opponents.
Jansson wasted a chance to make a big impression at the other end of the pitch when he rose unmarked at a corner but headed straight at the keeper.
With world champions Germany - smarting from their opening-game defeat - up next, this was a vital win for Sweden.
South Korea face battle to stay in World Cup
South Korea did not win a game at the 2014 World Cup and they now face a battle to qualify from a tough group after a lacklustre performance.
Having qualified by finishing second behind Iran in a six-team group, they were hoping to repeat their efforts of 2010 when they reached the last 16 in South Africa.
This was a lethargic display and their failure to test keeper Robin Olsen will be a big concern for boss Shin Tae-yong.
After an impressive season with Tottenham, Son Heung-min is hoping to make his mark in Russia but was largely anonymous other than one impressive run in the first half.
South Korea's day to forget was summed up when Hwang, who was unmarked, headed wide from eight yards.