Argentina are sweating over the fitness of right back Nicolas Burdisso ahead of their second round clash against Mexico.
The 25-year-old hobbled out of Argentina's 0-0 draw with Holland with a leg injury and now looks doubtful for their next game on Saturday.
Burdisso had also played in the first two games against Ivory Coast and Serbia & Montenegro and coach Jose Pekerman admits the injury is a major concern.
The manner in which he signalled to the bench was particularly alarming for Pekerman.
"We are worried because he would never normally want to come off and he is very important for us," said the coach.
"We will do tests in the morning and see what the doctors say but he doesn't have very long to recover.
"It would hurt us if he was injured."However, Pekerman was pleased with the contribution of Burdisso's replacement Fabricio Coloccini.
"There are always accidents, like what happened to Burdisso," he conceded.
"Coloccini going on left me with a very good feeling.