Champions in 1978 and 1986, Argentina are part of football's elite and have in their ranks Lionel Messi, the five-times world player of the year.
But they only qualified for Russia thanks to a win in their final qualifier against Ecuador and scored 19 goals in 18 games, the lowest by any South American qualifier since the single-group format was adopted in the mid-1990s.
Since then, their on the field woes have worsened - a slim win over non-qualifiers Italy in March was followed four days later by a 6-1 hammering by Spain - and been exacerbated by bad luck and poor planning.
Argentina lost their first-choice goalkeeper Sergio Romero to a knee injury and midfielder Manuel Lanzini withdrew after damaging ligaments nine days before the tournament.
They pulled themselves together to beat Haiti 4-0 but that did little to convince anxious fans.
Argentine preparations were dealt another blow when an ill-advised friendly against Israel in Jerusalem was cancelled due to political pressure.
In spite of all this, Argentina are still firm favourites in Moscow on Saturday to overcome the smallest nation ever to qualify for the World Cup finals.
Iceland were the surprise team at Euro 2016, drawing with winners Portugal in the group stage and defeating England in the last 16 on their way to quarter-final defeat by France.
But their form has dipped this year and they have failed to win any their last four matches, three of which they lost, to Mexico, Peru and Norway, by shipping three goals.
Key midfielder Gylfi Sigurdsson has missed most of the last three months with a knee injury. He made substitute appearances in Iceland's final two friendlies this month and his presence from the start would be a vital confidence booster.
Few people believe Iceland can win but they may take heart from recalling the last time Argentina expected to win the opening game of the tournament against a team who had never won a World Cup match.
The year was 1990 and Argentina's opponents were Cameroon who won 1-0 and went on to reach the quarter-finals, a feat still unsurpassed by an African side.
(Reporting by Andrew Downie, editing by Ed Osmond)
