Iceland's Johann Berg Gudmundsson doubtful for Nigeria clash with torn calf

Iceland pulled off a huge shock in its first-ever World Cup match on Saturday by holding Argentina to a 1-1 draw, but it might have come at a cost.

Johann Berg Gudmundsson suffered a torn calf muscle in the game and is currently being monitored by the team's medical staff, assistant coach Helgi Koldvidsson told reporters Wednesday, per the Press Association.

Iceland is set to face Nigeria on Friday, and may feel it needs to win to have a strong chance of progressing from Group D after Croatia's victory against the Super Eagles.

Koldvidsson was unsure of Gudmundsson's status for Friday, saying: "It remains a question whether he will be fit, but we'll see on matchday."

Gudmundsson is an integral player for the Nordic minnows, having won his 68th cap against Argentina. The Burnley midfielder's versatility has been a huge boost for his country in recent years; he can play on either wing, or in a more central role in attacking midfield.

The 27-year-old started all five games in Iceland's shock run to the quarter-final stage at its first-ever international tournament at Euro 2016, but managed just over an hour of Saturday's game before needing to be withdrawn.

After Nigeria on Friday, Iceland's third and final group-stage game will come against current Group D leader Croatia on Tuesday.