Park Joo-ho's World Cup campaign could be over after the defender sustained a suspected torn hamstring in South Korea's 1-0 defeat to Sweden on Monday.
Park overstretched when trying to keep the ball in play in Nizhny Novgorod and had to be replaced by Kim Min-woo in the 28th minute.
South Korea coach Shin Tae-yong thinks it could be a serious problem for the left-back.
"Park has hurt his hamstring. We think he might have hurt it very seriously. I think he probably tore it," Shin said after the game.
A penalty from Andreas Granqvist was enough to give Janne Andersson's side all three points in their opening Group F match.