Czech midfielder Vladimir Smicer has been ruled out of the World Cup finals due to a leg injury, the CTK news agency quoted the player as saying on Thursday.
"This morning I sat down with the doctors and we came to this decision. I couldn't let the coach, the players, or myself wait any longer," Smicer said.
"There are only 10 days to go until the first match and I still can't even train."
The Girondins Bordeaux player has been struggling for fitness since injuring a tendon behind his right knee in February.
Smicer was diagnosed with a blood clot in his thigh muscle by team doctors at the Czech Republic training camp in Austria last week after suffering discomfort.
The 33-year-old did not play in a 1-0 win against Costa Rica on Tuesday.
Rangers midfielder Libor Sionko is likely to be called up to replace Smicer. Sionko has been training with the team as coach Karel Brueckner included extra players in case replacements were needed.
Brueckner could, however, also decide to go with Sparta Prague's Tomas Sivok.
The Czechs open their World Cup campaign on June 12 against the United States. Italy and Ghana are also in the same group.