|Sweden vs South Korea Republic [1:0]|
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.
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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 at the top of Group F after the first round of matches.
enrik Larsson in 2002 against Nigeria
Gritty Swedes get vital winSweden reached Russia by beating France in a group game on the way to finishing above the Netherlands in the table and reach the play-offs, when they overcame Italy.
However, they arrived in Russia without a goal in their previous three matches and without Zlatan Ibrahimovic after his retirement from international football.
Indeed, Janne Andersson's team looked to be heading for a goalless draw until the second-half penalty - the seventh spot kick to be awarded at the tournament.
There was little doubt about the validity of the penalty as replays showed Claesson, who plays his club football in Russia, was clearly caught.
Granqvist, 33, kept his nerve to become the oldest player to score on his World Cup debut since Martin Palermo, who was 36 when he netted for Argentina in 2010.
In doing so it meant the proportion of the 26 goals scored so far at this World Cup from the penalty spot rose to 19%.
It was however a gritty rather than spectacular performance from the Swedes, who lost Manchester United centre-back Victor Lindelof on the morning of the game due to illness.
His place was taken by Pontus Jansson but the Leeds United defender had little to do against lacklustre opponents.
Jansson wasted a chance to make an 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 CupSouth Korea did not win a game at the 2014 World Cup and they now face a battle to qualify from a tough group after this lacklustre performance.
Having qualified by finishing second behind Iran in a six-team group, they were hoping to at least match their efforts of 2010 when they reached the last 16 in South Africa.
But 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 would expect to make a mark in Russia but he was largely anonymous other than one impressive run in the first half.
Only when they fell behind did South Korea add some much needed urgency into their play.
However, their day to forget was summed up when the unmarked Hwang headed wide from eight yards.
Man of the match - Cho Hyun-woo (South Korea)
'We need to dare to do even more' - what they said...Sweden coach Janne Andersson: "I felt the wait for the VAR was unnecessary. There was no doubt that the penalty should have been called straightaway. Luckily the referee had VAR to help him to be able to make the right decision.
"Today's match was so much more important to win after Germany lost. But we were focused on winning the game anyway. The opportunities for us now going forward are so much better.
"Germany are the ones faced with a dilemma. We are going to prepare in the best way possible and then we'll see. We need to dare to do even more."
Turning the clock back 60 years - the stats
- This was Sweden's first win in their opening match at a World Cup since beating Mexico 3-0 as hosts in 1958, drawing five and losing two since then.
- South Korea lost their opening match at a World Cup for the first time since 1998.
- Sweden's goal was the first they have scored in 402 minutes of international football.
- South Korea are winless in seven World Cup matches (D2 L5), losing their last three in a row.
What's next?Sweden face Germany in Sochi on Saturday 23 June (19:00 BST) while South Korea play at 16:00 on the same day against Mexico in Rostov-on-Don.