Some players grab a quick holiday between the end of the season and linking up for the World Cup duty.
We now take a look at 5 key players who will play a vital role in Saturday's David and Goliath encounter.
Iceland were aggressive and combative from the first minute and offered a threat on the break against Argentina's vulnerable back line. He has made 77 senior appearances for the national team and was made permanent captain in August 2012.
Even after drawing with eventual winners Portugal, beating England and giving hosts France a scare before defeat at Euro 2016, once Iceland were drawn in a group with Argentina, Croatia and Nigeria, three nations full of global quality, they were instantly written off. "It was our first game in a major tournament and they couldn't beat Iceland so it was not nice for them". They were very massive and intense against this star-studded Argentinian side.
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An increasingly dominant Spain did draw level in the 24th minute, though, with a goal that survived a VAR review. On Portugal's mindset: "We are 23 players and our head coach can only chose 11 to start the game with.
Sergio Aguero's emphatic finish gave Argentina the lead in the 19th minute, but that was cancelled out by Alfred Finnbogason just four minutes later. Can Leo Messi match the hat-trick scored by eternal rival Cristiano Ronaldo?
Argentina were awarded a penalty when Hordur Magnusson bundled over Aguero in the box, but the Messi's poor effort was saved by goalkeeper Hannes Thor Halldorsson. There's not much Messi will be able to do about the defense if those mistakes persist. Messi, who is Argentina's all-time leading goal scorer will be charged with scoring and creating the goals to push his country deep in the competition.
Macherano and Biglia will also start in midfield for Argentina.
Rurik Gislason came on for the injured Johann Berg Gudmundsson in an enforced Iceland change, and Messi curled a free kick over as he tried to make amends for his failure to score from the spot. When he is frustrated, he hunts the ball, and because Iceland were growing in confidence, he was finding himself further and further away from the goal.
What: Argentina will play Iceland in Group D play at the 2018 FIFA World Cup.