Argentina head coach Diego Maradona greets centre back Walter Samuel as he leaves the field with an injury on June 17. Samuel will likely miss the game with Mexico. ((Matt Dunham/Associated Press) )

Argentina defender Walter Samuel is almost certain to miss the round of 16 match against Mexico at the FIFA World Cup on Sunday in South Africa because of a right thigh injury.

Coach Diego Maradona says the centre back took part in a training session on Friday and initially looked good, but he doesn't want to take any risks with the player. Samuel went off injured in the 4-1 win over South Korea on June 17.

Nicolas Burdisso would fill in for Samuel, whose absence would be a concern for Maradona. The Argentines have looked formidable going forward, but at times shaky on defence.