MOSCOW -- Iceland manager Heimir Hallgrimsson said his entire squad is fit to play in Saturday's World Cup opener against Argentina, which he declared "the biggest game in the history of Iceland."

Midfielder Gylfi Sigurdsson and captain Aron Gunnarsson have both been recovering from knee injuries, with Sigurdsson missing the last two months of the Premier League season with Everton and Gunnarsson working his way back from knee surgery in late April.

Sigurdsson played a part in Iceland's two most recent friendlies, scoring in the 3-2 defeat to Norway on June 2 and then playing the first 67 minutes of the 2-2 draw with Ghana five days later, but Gunnarsson didn't feature in either match.

"Everyone is ready to play and everyone wants to play," Hallgrimsson said at a news conference. "It's a headache which a [manager] has to work on."

Gunnarsson, for his part, struck an optimistic tone in terms of his fitness.

"I'm feeling very good," the Cardiff City midfielder said. "I've been practicing well and a lot, and getting my previous strength again.

"Of course, I was racing against time, but I was not worried I wouldn't get it. You just have to do everything you have to do to become fit again when you have something like that. I'm ready for this game and I can't wait to take the team out on the pitch -- that is, if I get into the starting team."

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Hallgrimsson pushed back on the characterisation that his side's run to the quarterfinals of Euro 2016 and qualifying for the World Cup was a "miracle." Instead, he chalked up to steady progress that has taken place over a number of years.

"The team has been stable for the last four years," Hallgrimsson said. "We are 20th in the FIFA list and [have] won very important games. We won our group in the qualifying for the World Cup. We deserve to be here, so we do not see it as a miracle that we here in the World Cup."

Iceland will be facing Argentina, loaded with star players with edges in individual quality, in just about every position. Hallgrimsson knows that this leaves his side with little margin for error.

"Iceland can have the game of their lives tomorrow but still lose to Argentina," Hallgrimsson said. "That's just reality."

As for Lionel Messi, Hallgrimsson said he wouldn't man-mark the attacker, instead choosing to rely on a collective team effort.

"I don't have any magic formula," Hallgrimsson said about stopping Messi. "Everyone has tried everything against him and he always manages to score. He's one of the best players in the world. We'll do it like everything we do -- together. We'll help each other and try to do it as a team."

Iceland captain Aron Gunnarsson said he will be fit for the game against Argentina on Saturday. Sefa Karacan/Anadolu Agency/Getty Images

Hallgrimsson, quick to praise Argentina's whole squad, emphasised that Iceland can't just worry about Messi while ignoring others.

"If there is too much focus on one player then someone else will just take over and punish us," Hallgrimsson said.

One question facing Iceland is if they can improve on the quarterfinal finish at Euro 2016. Hallgrimsson insisted his vision for his team goes beyond just one tournament.

"The World Cup is huge, the biggest games we will play," he said. "But this is only June in 2018. Iceland doesn't stand and fall in three group games. For an underdog team, the worst thing is to stop and restart the engine. We have to look ahead and sustain what we are doing."

Yet Iceland remains the darling of the World Cup even before they have kicked a ball.

"You can't help but love Iceland," Hallgrimsson said. "We haven't attacked anyone; we haven't been at war with anyone. We have only had the Cod War and nobody got hurt there. It's a pretty little nation and pretty people in general. You can't help but love us."