Argentina: Jorge Sampaoli surprisingly named his starting lineup 24 hours before the game (see below), with Gonzalo Higuain, Paulo Dybala, Ever Banega and Giovani Lo Celso among those to miss out on a starting place.
Iceland: Talisman Gylfi Sigurdsson made his return form a knee injury against Ghana last week and is expected to start this one, though captain Aaron Gunnarsson is struggling with a muscle problem.
Argentina boss Jorge Sampaoli on Lionel Messi:
"It is true that the coach organises the team but the footballers create the opportunities on the pitch and if you have players like Messi then the coach has to organise players around him to take advantage of his amazing skills.
"He supports the team and the team supports him. Having a player like Leo means you have to organise the team differently.
"He's very fit, well prepared and looking forward to this World Cup and he hopes to be able to achieve his dream.
"He's a player who is very skilled so I don't think he's under pressure, he shouldn't be under pressure, he is a player who makes people very happy with his game.
"I don't think this should be Messi's last World Cup. His skills and the way he plays mean that he will be the one who decides.
"He is a genius and he plays like a genius, I don't think it will be his last."
Iceland boss Heimir Hallgrímsson:
"Regarding Messi, I don't have a magic formula. Everybody has tried everything against him and he always manages to score.
"He is one of the best players in the world. We will play against him like everything we do, we'll do it together. We'll help each other and try to do it as a team."
Did you know?
This will be the first ever meeting between the two sides.
Argentina have only lose one of their last seven World Cup gorup games against European opposition (W4, D2, L1).
Argentina confirmed XI: Caballero; Salvio, Otamendi, Rojo, Tagliafico; Mascherano, Biglia, Meza; Di Maria, Messi, Aguero.
Iceland possible XI: Halldorsson; Eyjolfsson, Arnason, Sigurdsson, Magnusson; Gudmunsson, Sigurdsson, Gunarsson, Hallfredsson, Bjarnason; Sigurdarson.