After single-handedly guiding Seleccao to the 2014 World Cup, Portugal captain Cristiano Ronaldo now makes his side sweat as the Real Madrid ace picks up a thigh injury.

Portuguese and Real Madrid star player Cristiano Ronaldo has brought worry to his national team as Los Blancos' ace picked up thigh injury, keeping him out of Portugal's friendly against Greece on Saturday.

The 29-year-old picked up this injury in Les Merengues' UEFA Champions League title-winning 4-1 defeat of La Liga neighbors, Atletico Madrid, in Lisbon last Saturday, forcing him to sit out Portugal's pre-match training sessions.

The 2013 Ballon d'Or winner is suffering from "myalgia (pain) in the posterior region of his left thigh" according to a statement, and is joined on the sidelines by Joao Moutinho, Raul Meireles, Hugo Almeida, and Rubon Amorim.

WORRYING: CR7 gets sidelined with a thigh injury 

FIFA World Cup Qualifiers, Portugal, Cristiano Ronaldo

FIFA World Cup Qualifiers, Portugal, Cristiano Ronaldo

Ronaldo is joined by Joao Moutinho (left), Raul Meireles, Hugo Almeida, and Rubon Amorim

 FIFA World Cup Qualifiers, Portugal, Cristiano Ronaldo, Joao Moutinho

The injuries to Paulo Bento's men, especially that of Cristiano Ronaldo, are not believed to be ones that will keep them out of football's grand tournament in Brazil, kicking off June 12.

However, with the Seleccao captain's poor injury track record this season, Portugal will be sweating to see whether his latest fitness issue will rob Bento of their all-time leading goal-scorer. 

Cristiano is all smiles in this picture but will he be frowning when Portugal take on Germany in their opening game?

FIFA World Cup Qualifiers, Portugal, Cristiano Ronaldo